土建外文翻譯---城市地下鐵道連拱隧道群施工技術(shù)研究

1、<p>　　Urban Underground Railroad arch tunnel Construction Technology Group</p><p>　　Abstract Project in Guangzhou Metro Line, right-arch construction method of tunnels to explore. Subway Construction i

2、n Guangzhou for the first time put forward a double-arch tunnel to single-hole tunnel construction technology, and a single type of wall and split in the wall structure, comparison and selection of Technology solutions w

3、ere obtained to meet the structural safety, construction safety and Economic benefits of better Technology solutions for the future design and construction of sim</p><p>　　Keywords: double-arch tunnel group;

4、 a single type of wall; construction Technology; split in the wall. </p><p>　　As the circuit design requirements subway tunnel, the tunnel structure produces a variety of forms, ranging from cross-sec

5、tion from double-arch and the three-arch tunnel composed of double-arch tunnel section is commonly used in the connection lines and crossing lines. In this paper, engineering examples, according to tunnel in which geolog

6、ical conditions, duration requirements, raised through the comparison and selection can achieve rapid construction and the purpose of construction cost saving</p><p>　　1 Project Overview</p><p>

7、　　Guangzhou Metro Line Road station turn-back line of sports for sports Road station after the return line, structure complex, DK3 016.047 ~ 037.157 varying cross-section set the double-arch structure, three-arch structu

8、re of tunnels. Ranging from cross-arch tunnel excavation span 20.1m, excavation height of 10.076m, cross-vector ratio of 1:0.5, after lining a hole span 5.2m, large holes, after lining span 11.4m, the wall thickness of 1

9、.6 m. Three double-arch tunnel excavation span 19.9m, excavati</p><p>　　Section 2 dual-arch construction scheme comparison</p><p>　　As the double-arch tunnel segment structure more complex, the

10、tunnel cross-section changes in large, complicated construction process, construction was very difficult, the construction cycle is long, so I chose a good quality and efficient completion of the construction program seg

11、ment arch tunnel construction is particularly important. Selection of a construction program, the main consideration the following aspects: (1) construction safety and structural safety; (2) construction difficulties; &l

12、t;/p><p>　　2.1 a single type of wall construction plan </p><p>　　The program's main construction steps and measures are as follows: </p><p>　　(1) The right line of double-a

13、rch tunnel hole within the return line side of temporary construction access, dual-arch and the three-arch in the wall construction, is completed in a timely support for the wall, the construction to prevent bias.

14、 </p><p>　　(2) construction of the wall lining is completed, according to "first small then big, closed into a ring" principle, the right line with the step method of construction, with CRD enginee

15、ring method returned a four-lane span tunnel construction. </p><p>　　(3) When the return line side of the construction to the three-arch tunnel in the wall, then in accordance with the right line of t

16、he wall construction method and the three-arch-arch in the wall construction, during which the right line to stop excavation until the completion of construction of the wall. </p><p>　　(4) The return

17、line side of the wall construction is completed, the right line to continue to move forward the construction. </p><p>　　The construction method for the domestic double-arch tunnel of conventional cons

18、truction method, Guangzhou Metro, Nanjing and Beijing Metro subway both applications, and can secure successful completion of the construction of tunnels. However, examples of past engineering and construction Technology

19、 research can be found, the program has weaknesses and shortcomings. </p><p>　　(1) The program used in this project, in a short span of 21.11m of double-arch tunnel, the tunnel's opening between the

20、 supporting and secondary lining will be converted four times, the conversion too frequently. </p><p>　　(2) wall and side holes covered by waterproof layer of tunnel lining construction, steel enginee

21、ring, formwork, concrete pouring required multiple conversions, the construction period up to 2 months. </p><p>　　(3) The lining is completed, the wall of anti-bias materials, equipment, support and i

22、nput, resulting in higher construction costs, Economic efficiency will drop. </p><p>　　2.2 The split in the wall construction plan </p><p>　　The program's main construction steps and

23、measures are as follows: </p><p>　　(1) ranging from cross-double-arch tunnel into two single-hole, change the formula for the separation wall, the first line of one-way right-forward construction of t

24、he tunnel. </p><p>　　(2) three arch tunnel in the wall to make the first non-Shi lining, according to single-line working condition through. </p><p>　　(3) the right line of large-s

25、ection double-arch tunnel wall construction method adopted in accordance with CRD. </p><p>　　(4) The return line is in accordance with the right line of the opposite side of the construction sequence

26、of construction. </p><p>　　Adoption of this program is in fact a one-way in accordance with the construction of two methods, compared with the previous one, after the program has the following advanta

27、ges:</p><p>　　(1) reduction of the construction process to speed up the convergence process conversion. </p><p>　　(2) reduce the construction difficulty, shortening the construction cycle

28、. </p><p>　　(3) reduce the construction costs and improve Economic efficiency. </p><p>　　(4) change a single type of wall to separate the wall, completely solved the structure of d

29、ouble-arch tunnel waterproofing defects. </p><p>　　(5) The three-arch tunnel in the latter pArt of the construction hole, equivalent to large-span rock tunnels reserved for the core is conducive to bo

30、th sides of the double-arch tunnel construction safety (Table 1). </p><p>　　Section 3 three-arch construction plan </p><p>　　Right-line direct access to three double-arch tunnel, the Supp

31、ort parameters to the original designs for grating erection of the whole ring, according to design the whole ring of shotcrete, and enhance the bolt at the wall vault settings (return right side Tong Line Construction me

32、thod), wall construction in the tunnel when you need to get rid of Office, located at a vertical grill joints strengthened beam. </p><p>　　Strict control of excavation footage of each cycle, grid spa

33、cing of 0.6m / Pin. Weak in the wall excavation using millisecond blasting program (conditional maximize the use of static blasting programs), minimize the wall rock and the lining of the tunnel has been disturbed, to en

34、sure construction safety. The completion of excavation in the wall immediately after the secondary lining. After the completion of construction of the wall in wall voids of the backfilling, plus jack supports. The side o

35、</p><p>　　4 construction of the force structure of Behavior Analysis </p><p>　　Across the range of the double-arched wall canceled, changed to separate the wall, in the domestic urban unde

36、rground railway engineering has not yet been a similar engineering design and construction experience, there is no such tunnel structure design, and therefore the structure is safe, as well as the course of construction

37、conversion process of construction is safe, the program will be the focus of the study. </p><p>　　Application of ANSYS finite element software for common procedures ranging from cross-arch tunnel nume

38、rical simulation, using stratigraphic - structural model of the structure of the tunnel by the force and deformation analysis (Figure 1, Figure 2, Figure 3). The scope of the horizontal direction taken by force along the

39、 direction of the tunnel cross-section to cross-hole 3 times the limit, taking the top of the vertical direction to the surface, the bottom-hole span to 3 times the limit, unit m</p><p>　　5 Construction of k

40、ey technologies and corresponding measures </p><p>　　Arch tunnel construction segment is required on a strict construction organization and strong technical assurance measures carried out under the go

41、od job in organizing the construction of steps to prepare the construction of a variety of technical preventive measures are key to success.</p><p>　　5.1 pairs of pull anchor and strengthen the bolt &

42、lt;/p><p>　　Abolition of a single type of wall, the excavation is complete in the wall thickness of 0.8m, pull anchor and strengthen the right bolt set is very necessary. Φ22 steel bolt used on the pull bolt dr

43、ug volume, pitch, 0.6m × 0.5m, the length of the wall thickness according to the 0.8 ~ 2.0m. Strengthen the bolt in the wall located at the invert and side walls at both sides, using 3.0m of Φ25 hollow grouting anch

44、or, spacing 0.6m × 0.8m. </p><p>　　5.2 in the body wall, grouting rock block folders </p><p>　　In the wall of rock thinnest Department to 0.15m, after repeated blasting excavation pro

45、cess, the impact of the rock wall around the loose, their bearing capacity affected. Therefore, we must separate the wall in the vault, wall, invert Department for loose rock for grouting. Φ42 embedded steel, cement slur

46、ry to take - water glass pairs of liquid slurry, the parameter of 1:1 cement and 30 ~ 45Be sodium silicate solution, grouting pressure of 0.2 ~ 1.0MPa. In both excavation grouting in the wall </p><p>　　5.3 m

47、illisecond blasting technology microseisms </p><p>　　Tunnel excavation construction method used in all drilling and blasting. Because the lot is located in downtown Guangzhou, the ground-intensive bui

48、ldings, and the Tunnel "0" spacing excavation, blasting must be set aside in accordance with glossy layer of smooth microseismic millisecond blasting program construction blasting vibration control will be allo

49、wed within the . For the double-arch tunnel in which strata of Ⅲ, Ⅳ grade rock blasting to take measures as follows: </p><p>　　(1) The blasting equipment, using low-speed emulsion explosive shock.

50、 </p><p>　　(2) strict control of footage per cycle (0.6 ~ 0.8m), around the borehole spacing of 0.4m, reduce the loading dose to control the smooth blasting effect (Figure 4). </p><p>　

51、　(3) The use of multiple detonators per blast detonation, using non-electric millisecond detonator initiation network asymmetric micro-vibration technology. </p><p>　　(4), excavation and construction

52、of the wall at the second to take first reserve 1m smooth layer, Cutting away from the eyes arranged in the side of the wall on the second floor reserved for smooth blasting around the eyes more than surface layout of th

53、e empty eyes, a small charge. Put an end to ultra-digging, digging, when partially due to artificial air pick excavation. </p><p>　　Through the above effective measures, in the wall during the constru

54、ction of the second blast, right in the thick wall of 0.15m basic did not cause damage to the smooth passage of the double-arch tunnel "0" from the excavation.</p><p>　　5.4 Auxiliary scissors to st

55、rengthen supporting </p><p>　　By ANSYS simulation analysis, in order to ensure that small section of tunnel construction safety, the need for auxiliary support of small section tunnel reinforcement to

56、resist the impact of blasting and rock produced by the instantaneous release of excavation loads generated by bias. </p><p>　　Supporting materials, using I20 steel, welded steel plate embedded in the

57、 grille on both ends, using high-strength bolt reinforcement. Support arrangement spacing of 0.6m, which are arranged on a grid for each Pin, arranged to extend the scope to a double-arch on each side of 1.2m, and the co

58、mpletion of the excavation before the big end. The height and angle of support arrangements to ensure the smooth passage of construction machinery and equipment. Through the construction of proof, supporting</p>&

59、lt;p>　　5.5 Information Construction </p><p>　　In order to ensure structural safety and construction safety, in the tunnel construction process to carry out real-time monitoring measurements to stud

60、y the supporting structure and the surrounding strata deformation characteristics to predict the corresponding supporting structure deformation and verify that the supporting structure is reasonable, for the information

61、technology provide the basis for the construction. Construction Monitoring and Measurement shows a small section of the tunnel ma</p><p>　　6 Construction Summary </p><p>　　Through this pr

62、oject example, proved that the use of separate programs to ensure that the wall construction of tunnels section of arch construction safety and structural safety, duration of more than a single type of wall construction

63、program faster 1.0 to 1.5 months. This project for similar future subway construction has achieved successful experiences and Application examples. </p><p>　　By summarizing the analysis, the following

64、conclusions: </p><p>　　(1) In accordance with the actual geological conditions boldly changed a single type of double-arched wall to separate the construction of walls, similar to conventional ultra-s

65、mall-distance tunnel construction, eliminating double-arch tunnel Construction of the wall must be of conventional construction method, the final lining of structural forces has little effect on the structure of water is

66、 more favorable, and shorten the construction duration. Through the construction of this project in two</p><p>　　(2) The construction of the key technology is to reduce the damage and disturbance of surround

67、ing rock, as well as the protection of the tunnel structure has been forming. Therefore, in the double-arched wall at the weak control of a weak good millisecond blasting will be the focus of the success of the construct

68、ion. Smooth layer of smooth blasting using reserved achieved the desired results. If the reserved right to take a static smooth layer of rock blasting will be even better. </p><p>　　(3) to strengthen the wea

69、k in the wall is also supporting the construction of this important reasons for the success. From the mechanical analysis of view, invert the junction with the side walls are most affected, ensuring adequate capacity to

70、withstand the initial load supporting; second is to strengthen the body in the clip rock column grouting reinforcement of its use of the pull bolt, strengthening bolt and grouting reinforcement, ensuring the stability of

71、 surrounding rock. Used in the cons</p><p>　　(4) reasonably arrange construction sequence so that all processes in the conversion with minimal impact during the construction of each other. </p><p

72、>　　References </p><p>　　[1] LIU Xiao-bing. Double-arch tunnel in the form of wall-structured study [J]. Construction Technology 2004-10, 15 </p><p>　　[2] Wang Junming. Weak rock sections doub

73、le-arch tunnel Construction Technology [J]. Western Exploration Engineering, 2003-06 </p><p>　　[3] GB50299-1999 underground railway Engineering Construction and acceptance of norms [S]. Beijing: China Planni

74、ng Press, 1999 </p><p>　　城市地下鐵道連拱隧道群施工技術(shù)研究</p><p>　　摘要：利用廣州地鐵工程實(shí)例,對(duì)連拱隧道群施工工法進(jìn)行探討。在廣州地鐵施工中首次提出了將連拱隧道改為單洞隧道施工技術(shù)，并對(duì)單一式中墻和分離式中墻結(jié)構(gòu)的技術(shù)方案進(jìn)行了比選，得出了滿(mǎn)足結(jié)構(gòu)安全、施工安全和經(jīng)濟(jì)效益較好的技術(shù)方案，可為今后類(lèi)似工程的設(shè)計(jì)和施工提供借鑒和參考。</p>

75、;<p>　　關(guān)鍵詞：連拱隧道群；單一式中隔墻；分離式中隔墻；施工技術(shù)。</p><p>　　地鐵隧道由于線(xiàn)路設(shè)計(jì)要求，產(chǎn)生多種隧道結(jié)構(gòu)形式，其中由不等跨雙連拱和三連拱隧道組成的連拱隧道段常用于正線(xiàn)和渡線(xiàn)的連接。本文結(jié)合工程實(shí)例，根據(jù)隧道所處地質(zhì)條件、工期要求，通過(guò)比選提出了可達(dá)到快速施工和節(jié)省施工成本目的的最佳施工方案。</p><p><b>　　1 工程概況&

76、lt;/b></p><p>　　廣州地鐵三號(hào)線(xiàn)體育西路站折返線(xiàn)為體育西路站站后折返線(xiàn)，結(jié)構(gòu)形式復(fù)雜，在 DK3+016.047~+037.157段設(shè)置了不等跨雙連拱結(jié)構(gòu)、三連拱結(jié)構(gòu)等隧道群。不等跨連拱隧道開(kāi)挖跨度為20.1m，開(kāi)挖高度為 10.076m，跨矢比為1∶0.5，小洞襯砌后跨度為5.2m，大洞襯砌后跨度為11.4m，中墻厚度為1.6m。三連拱隧道開(kāi)挖跨度為19.9m，開(kāi)挖高度為7.885m，跨矢

77、比為1∶0.1。連拱隧道段的圍巖自上而下有：人工填土層、沖—洪積砂層、沖積—洪積土層、河湖相沉積土層、可塑狀殘積土、硬塑—堅(jiān)硬狀殘積土、全風(fēng)化巖層、強(qiáng)風(fēng)化巖層、中風(fēng)化層和微風(fēng)化層。隧道通過(guò)地層巖質(zhì)較為均一，強(qiáng)度較高，承載能力強(qiáng)，穩(wěn)定性好。隧道拱頂覆蓋層厚度為15.5~18m，其中拱頂Ⅳ級(jí)圍巖層厚度為5.6~7.6m。連拱隧道段地下水埋深為2.28~4.1m，主要是第四系孔隙水和裂隙水。</p><p>　　2 雙

78、連拱段施工方案比選</p><p>　　由于連拱隧道段結(jié)構(gòu)比較復(fù)雜，隧道斷面變化較大，施工工序繁復(fù)，施工難度高，施工周期長(zhǎng)，所以選擇一個(gè)好的施工方案對(duì)優(yōu)質(zhì)高效完成連拱隧道段的施工尤為重要。選擇施工方案時(shí)主要考慮以下幾個(gè)方面：(1)施工安全和結(jié)構(gòu)安全；(2)施工難度；(3)施工周期；(4)經(jīng)濟(jì)效益。本著這四條原則,經(jīng)過(guò)施工方案的研究和論證，選出下面兩個(gè)施工方案進(jìn)行比較甄選。</p><p>

79、　　2.1 單一式中墻施工方案</p><p>　　該方案的主要施工步驟及措施如下：</p><p>　　(1)從右線(xiàn)雙連拱小洞隧道內(nèi)向折返線(xiàn)側(cè)進(jìn)行臨時(shí)施工通道、雙連拱和三連拱中墻施工，完成后中墻及時(shí)支撐，施工時(shí)防止偏壓。</p><p>　　(2)中墻襯砌施工完成后，按照“先小后大、封閉成環(huán)”的原則，用臺(tái)階法進(jìn)行右線(xiàn)施工，用CRD工法進(jìn)行折返線(xiàn)大跨度隧道施工。&l

80、t;/p><p>　　(3)當(dāng)折返線(xiàn)側(cè)施工到三連拱隧道中墻后，再按照右線(xiàn)中墻施工方法進(jìn)行三連拱和雙連拱中墻施工，這期間右線(xiàn)停止掘進(jìn)，直到中墻施工完成。</p><p>　　(4)折返線(xiàn)側(cè)中墻施工完成后,右線(xiàn)繼續(xù)往前施工。</p><p>　　該工法為國(guó)內(nèi)連拱隧道常規(guī)施工工法，廣州地鐵、南京地鐵和北京地鐵中均有應(yīng)用，并能安全順利地完成隧道群的施工。但是對(duì)以往的工程實(shí)例和施

81、工技術(shù)的研究可以發(fā)現(xiàn)，該方案還存在不足和缺陷。</p><p>　　(1)本方案運(yùn)用于本工程上，在短短的21.11m的連拱隧道內(nèi)，隧道的初期支護(hù)和二次襯砌間將轉(zhuǎn)換4次， 轉(zhuǎn)換過(guò)于頻繁。</p><p>　　(2)中墻和邊洞隧道襯砌涉及的防水層施工、鋼筋工程、模板工程、混凝土澆注均需多次轉(zhuǎn)換，施工周期長(zhǎng)達(dá)2個(gè)月。</p><p>　　(3)襯砌完成后，中墻防偏壓支撐和

82、材料設(shè)備的投入，導(dǎo)致施工成本增高，經(jīng)濟(jì)效益降低。</p><p>　　2.2 分離式中墻施工方案</p><p>　　該方案的主要施工步驟及措施如下：</p><p>　　(1)將不等跨雙連拱隧道改為兩個(gè)單洞,變更為分離式中墻，先從右線(xiàn)單線(xiàn)隧道往前施工。</p><p>　　(2)對(duì)三連拱隧道先不施作中墻襯砌,按單線(xiàn)工況通過(guò)。</p&g

83、t;<p>　　(3)對(duì)右線(xiàn)的大斷面雙連拱隧道按照CRD工法側(cè)壁通過(guò)。</p><p>　　(4)折返線(xiàn)側(cè)則按照右線(xiàn)相反的施工順序進(jìn)行施工。</p><p>　　采用本方案實(shí)際就是按照兩條單線(xiàn)的施工方法進(jìn)行，與上一方案進(jìn)行對(duì)比后，具有如下優(yōu)點(diǎn)：</p><p>　　(1)減少施工工序，加快工序的銜接轉(zhuǎn)換。</p><p>　　(

84、2)降低了施工難度，縮短了施工周期。</p><p>　　(3)降低了施工成本，提高了經(jīng)濟(jì)效益。</p><p>　　(4)變單一式中墻為分離式中墻，徹底地解決了連拱隧道結(jié)構(gòu)的防水上的缺陷。</p><p>　　(5)三連拱隧道中洞后期施工，相當(dāng)于大跨度隧道預(yù)留了核心巖體，有利于兩側(cè)雙連拱隧道施工安全。</p><p>　　3 三連拱段施工方

85、案</p><p>　　從右線(xiàn)直接進(jìn)入三連拱隧道，其支護(hù)參數(shù)以原設(shè)計(jì)進(jìn)行，格柵全環(huán)安設(shè)，按設(shè)計(jì)全環(huán)噴射混凝土，并加強(qiáng)中墻拱頂處的錨桿設(shè)置(折返側(cè)同右線(xiàn)施工方法)，在中墻施工時(shí)需要破除隧道格柵接頭處設(shè)一縱向加強(qiáng)梁。</p><p>　　嚴(yán)格控制每循環(huán)開(kāi)挖進(jìn)尺，格柵間距為0.6m/榀。中墻開(kāi)挖采用微差弱爆破方案(有條件盡量采用靜態(tài)爆破方案)，最大限度地減少對(duì)中墻巖層和已襯砌隧道的擾動(dòng),確保施工

86、安全。中墻開(kāi)挖完成后，立即進(jìn)行二次襯砌。中墻施工完成后對(duì)中墻空隙進(jìn)行回填，加千斤頂支護(hù)。一側(cè)施工完成后，才進(jìn)行另一側(cè)中墻施工。當(dāng)兩側(cè)中墻施工完成后，及時(shí)進(jìn)行兩側(cè)單洞隧道的二次襯砌，然后進(jìn)行三連拱隧道中間巖體的開(kāi)挖和襯砌。施工中應(yīng)特別注意三連拱隧道中墻處的沉降和收斂變形，如出現(xiàn)異?，F(xiàn)象，立即進(jìn)行加固處理。</p><p>　　4 施工時(shí)結(jié)構(gòu)受力性態(tài)分析</p><p>　　將不等跨雙連拱的中

87、墻取消，改為分離式中墻，在國(guó)內(nèi)城市地下鐵道工程中尚未有類(lèi)似工程設(shè)計(jì)及施工經(jīng)驗(yàn)，也沒(méi)有類(lèi)似隧道結(jié)構(gòu)設(shè)計(jì)，因此結(jié)構(gòu)是否安全，以及施工過(guò)程中工序轉(zhuǎn)換時(shí)施工是否安全，將是本方案研究的重點(diǎn)。</p><p>　　應(yīng)用ANSYS有限元通用程序軟件對(duì)不等跨連拱隧道進(jìn)行數(shù)值模擬計(jì)算，采用地層-結(jié)構(gòu)的模式對(duì)隧道結(jié)構(gòu)的受力和變形進(jìn)行分析。所取受力范圍水平方向沿隧道橫斷面方向以洞跨的3倍為限，垂直方向上方取至地表、下方以洞跨的3倍為限

88、，單元模型采用DP地層材料的彈塑性實(shí)體，隧道襯砌采用彈性梁?jiǎn)卧M,梁?jiǎn)卧蛯?shí)體單元采用藕合方程連接。通過(guò)表2中的數(shù)據(jù)分析可以看出，大隧道在施工時(shí)對(duì)小隧道的影響較大，如果對(duì)小斷面隧道采用必要的加強(qiáng)措施，并控制臨時(shí)支撐的縱向拆除間距，該方案是有益并可行的。</p><p>　　5 施工關(guān)鍵技術(shù)及對(duì)應(yīng)措施</p><p>　　連拱隧道段的施工是需要在嚴(yán)密的施工組織和強(qiáng)有力的技術(shù)保證措施下進(jìn)行的

89、，組織好各施工步驟，準(zhǔn)備好各種技術(shù)預(yù)防措施是施工成功的關(guān)鍵。</p><p>　　5.1 對(duì)拉錨桿及加強(qiáng)錨桿</p><p>　　取消單一式中墻后,開(kāi)挖完成后中墻厚度為0.8m，對(duì)拉錨桿和加強(qiáng)錨桿的設(shè)置是非常必要的。對(duì)拉錨桿采用Φ22鋼筋藥卷錨桿，間距為0.6m×0.5m, 長(zhǎng)度根據(jù)中墻的厚度變化為0.8~2.0m。加強(qiáng)錨桿設(shè)于中墻兩側(cè)仰拱和邊墻處，采用3.0m的Φ25中空注漿錨

90、桿，間距0.6m×0.8m。</p><p>　　5.2 中墻夾巖柱體注漿加固</p><p>　　中墻巖體最薄處為0.15m,經(jīng)過(guò)多次爆破開(kāi)挖過(guò)程的影響，中墻周?chē)膰鷰r松動(dòng)，其承載力受影響。因此,必須分別在中墻拱頂、墻、仰拱處對(duì)松動(dòng)圍巖進(jìn)行注漿。預(yù)埋Φ42鋼管,漿液采取水泥-水玻璃雙液漿，參數(shù)為1∶1水泥漿和30~45Be水玻璃溶液，注漿壓力為0.2~1.0MPa。在兩次開(kāi)挖中

91、中墻均進(jìn)行注漿,最后開(kāi)挖完成后對(duì)中墻夾層進(jìn)行飽和注漿。</p><p>　　5.3 微差微震爆破技術(shù)</p><p>　　隧道開(kāi)挖全部采用鉆爆法施工。由于地處廣州市繁華地段，地面建筑物密集，且隧道采用“0”間距開(kāi)挖，爆破時(shí)必須按照預(yù)留光面層光面微震微差爆破方案進(jìn)行施工，將爆破震動(dòng)控制在容許范圍內(nèi)。對(duì)于連拱隧道所處地層為Ⅲ、Ⅳ級(jí)圍巖采取的爆破措施為：</p><p>

92、　　(1)爆破器材采用低震速乳化炸藥。</p><p>　　(2)嚴(yán)格控制每循環(huán)進(jìn)尺(0.6~0.8m)，周邊炮眼間距為0.4m，減少裝藥量，控制光面爆破效果。</p><p>　　(3)每次爆破使用多段位雷管起爆，采用非電毫秒雷管不對(duì)稱(chēng)起爆網(wǎng)路微震動(dòng)技術(shù)。</p><p>　　(4)中墻處采取二次開(kāi)挖施工，先預(yù)留1m光面層，掏槽眼布置在遠(yuǎn)離中墻的一側(cè)，對(duì)預(yù)留的光面

93、層二次爆破時(shí)周邊眼光面層多布置空眼、少裝藥。杜絕超挖，局部欠挖時(shí)采用人工風(fēng)鎬開(kāi)挖。</p><p>　　通過(guò)以上有效措施，在中墻二次爆破施工時(shí)，對(duì)0.15m厚的中墻基本未造成破壞，順利通過(guò)了連拱隧道的“0”距離開(kāi)挖。</p><p>　　5.4 輔助剪刀撐加強(qiáng)支護(hù)</p><p>　　通過(guò)ANSYS模擬分析，為確保小斷面隧道施工安全，必須對(duì)小斷面隧道進(jìn)行輔助支撐加固

94、，抵御爆破產(chǎn)生的瞬時(shí)沖擊和巖層開(kāi)挖時(shí)荷載釋放產(chǎn)生的偏壓。</p><p>　　支撐材料采用I20型鋼,焊接于兩端格柵預(yù)埋鋼板上，并采用高強(qiáng)螺栓加固。支撐布置間距為0.6m，即每一榀格柵上均布置，布置范圍延長(zhǎng)至雙連拱兩邊各 1.2m，并在開(kāi)挖大端面前完成。支撐布置的高度和角度要確保施工機(jī)械設(shè)備能順利通行。通過(guò)施工證明，支撐的設(shè)置是必要和有效的，小斷面隧道在加設(shè)輔助剪刀撐后收斂?jī)H為5mm。</p>&l

95、t;p><b>　　5.5 信息化施工</b></p><p>　　為確保結(jié)構(gòu)安全和施工安全，在隧道施工過(guò)程中開(kāi)展實(shí)時(shí)監(jiān)控量測(cè)，研究支護(hù)結(jié)構(gòu)和周邊地層的變形特征，預(yù)測(cè)相應(yīng)的支護(hù)結(jié)構(gòu)變位并驗(yàn)證支護(hù)結(jié)構(gòu)的合理性，為信息化施工提供依據(jù)。施工中監(jiān)控量測(cè)顯示，小斷面隧道最大沉降為14.6mm，大斷面隧道最大沉降為17.2mm，結(jié)構(gòu)收斂最大值為7.6mm，地面最大沉降為10mm，三連拱中洞開(kāi)挖拱頂

96、最大沉降為22.8mm。</p><p><b>　　6 施工總結(jié)</b></p><p>　　通過(guò)本工程實(shí)例，證明了采用分離式中墻施工方案能夠保證連拱隧道群段的施工安全和結(jié)構(gòu)安全，工期比采用單一式中墻施工方案快1.0~1.5個(gè)月。本工程為今后類(lèi)似的地下鐵道建設(shè)取得了成功的經(jīng)驗(yàn)和應(yīng)用實(shí)例。</p><p>　　通過(guò)總結(jié)分析，得出以下結(jié)論：<

97、;/p><p>　　(1)根據(jù)實(shí)際地質(zhì)情況大膽地改雙連拱單一式中墻為分離式中墻進(jìn)行施工，類(lèi)似于常規(guī)的超小凈距隧道施工，摒棄雙連拱隧道必須先施工中墻的常規(guī)工法，對(duì)最終襯砌結(jié)構(gòu)受力影響較小，對(duì)結(jié)構(gòu)防水更有利，并且縮短了施工工期。通過(guò)本工程的兩次施工，實(shí)現(xiàn)了超小間距隧道“0”間距開(kāi)挖施工技術(shù)的重大突破。</p><p>　　(2)施工中的關(guān)鍵技術(shù)是減少?lài)鷰r的破壞及擾動(dòng)，以及對(duì)已經(jīng)成型隧道結(jié)構(gòu)的保護(hù)。

98、因此在雙連拱薄弱的中墻處控制好微差弱爆破將是施工取得成功的重點(diǎn)。采用預(yù)留光面層光面爆破取得了理想的效果。如果對(duì)預(yù)留的光面層巖體采取靜態(tài)爆破將更加理想。</p><p>　　(3)對(duì)薄弱中墻的加強(qiáng)支護(hù)也是本次施工取得成功的重要原因。從受力分析看，仰拱與側(cè)墻連接處受影響最大，確保了初期支護(hù)承受足量荷載；其次是加強(qiáng)對(duì)中夾巖柱體的注漿加固，對(duì)其采用對(duì)拉錨桿、加強(qiáng)錨桿和注漿加固,確保了圍巖的穩(wěn)定。施工采用的對(duì)拉錨桿如果充分

99、運(yùn)用預(yù)應(yīng)力加固,效果可能會(huì)更好。</p><p>　　(4)合理安排好施工先后順序，使各工序在轉(zhuǎn)換施工時(shí)相互影響最小。</p><p>　　參考文獻(xiàn)[1]劉小兵.雙跨連拱隧道中墻結(jié)構(gòu)合理形式研究[J].施工技術(shù),2004-10,15[2]汪俊明.軟弱圍巖地段雙連拱隧道施工技術(shù)[J].西部探礦工程,2003-06[3]GB50299-1999　地下鐵道工程施工及驗(yàn)收規(guī)范[S].北京:中