现代隧道技术
現代隧道技術
현대수도기술
Modern Tunnelling Technology
2015年
4期
158-164
,共7页
泥水盾构%砂土地层%最大支护压力%渗透破坏%实用计算方法
泥水盾構%砂土地層%最大支護壓力%滲透破壞%實用計算方法
니수순구%사토지층%최대지호압력%삼투파배%실용계산방법
Slurry shield tunnel%Sand strta%Maximum support pressure%Seepage failure%Practical calculation method
泥水盾构支护压力的上、下限值是确定合理支护压力的关键依据。文章通过对泥水盾构施工过程中的掘削面稳定机制进行分析后发现，在浅覆土砂层地段中，地层产生击穿破坏必须具备三个条件：(1)泥浆失水严重或者直接向地层中渗透，引起地层中超净孔隙水压的急剧升高；(2)较高的支护压力使得泥水具有良好的定向性，并与地层中的静止水压之间形成足够大的压力差；(3)覆土地层具有足够小的渗透系数，不至于使泥水直接从地层中渗流扩散，能在土颗粒的接触部位形成极高的水压力梯度。其实质就是由于高压泥浆直接向地层中入渗，引起覆土地层中超净孔隙水压升高，在地层中形成较大的水头差从而产生渗透破坏。据此提出了一种物理意义明确、操作简单的最大支护压力实用计算方法，该方法所需参数较少并能方便、快捷地根据常规土工试验获得。结合某过江隧道的工程实践，对最大支护压力进行了计算并与实际工程进行了对比，验证了这一计算方法的合理性与有效性。
泥水盾構支護壓力的上、下限值是確定閤理支護壓力的關鍵依據。文章通過對泥水盾構施工過程中的掘削麵穩定機製進行分析後髮現，在淺覆土砂層地段中，地層產生擊穿破壞必鬚具備三箇條件：(1)泥漿失水嚴重或者直接嚮地層中滲透，引起地層中超淨孔隙水壓的急劇升高；(2)較高的支護壓力使得泥水具有良好的定嚮性，併與地層中的靜止水壓之間形成足夠大的壓力差；(3)覆土地層具有足夠小的滲透繫數，不至于使泥水直接從地層中滲流擴散，能在土顆粒的接觸部位形成極高的水壓力梯度。其實質就是由于高壓泥漿直接嚮地層中入滲，引起覆土地層中超淨孔隙水壓升高，在地層中形成較大的水頭差從而產生滲透破壞。據此提齣瞭一種物理意義明確、操作簡單的最大支護壓力實用計算方法，該方法所需參數較少併能方便、快捷地根據常規土工試驗穫得。結閤某過江隧道的工程實踐，對最大支護壓力進行瞭計算併與實際工程進行瞭對比，驗證瞭這一計算方法的閤理性與有效性。
니수순구지호압력적상、하한치시학정합리지호압력적관건의거。문장통과대니수순구시공과정중적굴삭면은정궤제진행분석후발현，재천복토사층지단중，지층산생격천파배필수구비삼개조건：(1)니장실수엄중혹자직접향지층중삼투，인기지층중초정공극수압적급극승고；(2)교고적지호압력사득니수구유량호적정향성，병여지층중적정지수압지간형성족구대적압력차；(3)복토지층구유족구소적삼투계수，불지우사니수직접종지층중삼류확산，능재토과립적접촉부위형성겁고적수압력제도。기실질취시유우고압니장직접향지층중입삼，인기복토지층중초정공극수압승고，재지층중형성교대적수두차종이산생삼투파배。거차제출료일충물리의의명학、조작간단적최대지호압력실용계산방법，해방법소수삼수교소병능방편、쾌첩지근거상규토공시험획득。결합모과강수도적공정실천，대최대지호압력진행료계산병여실제공정진행료대비，험증료저일계산방법적합이성여유효성。
The upper and lower limits of support pressure are key for determining the reasonable support pressure of slurry shields. Based on an analysis of the stability mechanism of the working face during slurry shield operation, it is determined that there are three necessary conditions for ground breakdown failure in shallow-buried sand strata: 1) severe slurry dehydration or slurry penetration directly into the ground, causing a drastic increase of the extra-static pore water pressure; 2) good directionality of the slurry with a great pressure difference compared with that of static water pressure in the ground due to higher support pressure; and 3) a permeability coefficient of the overburden that is too small to cause slurry directly seeps and diffuses into the ground, creating an extremely high water pressure gradient at the contact site of the soil particles, which means that the extra-static pore water pressure increases along with the high-pressure slurry permeating directly into the ground, and seepage failure occurs thereafter due to large water head difference. Accordingly, a practical calculation method of maximum support pressure, which is convenient and requires fewer parameters, is proposed. The maximum support pressure is calculated and a comparison with a practice case is carried out based on a certain river-crossing tunnel project, verifying the rationality and effectiveness of the method.
