土压平衡盾构改良渣土力学行为及其地层响应特征  

Conditioned soils mechanical behavior of earth pressure balance shield tunneling and its impact on formation response

作　　者：肖超[1] 阳军生[1] 王树英[1] 何杰[2] 叶新宇 

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]湖南工业大学土木工程学院,湖南株洲412007 [3]Department of Civil, Surveying and Environmental Engineering, University of Newcastle, NSW 2308, Australia

出　　处：《中南大学学报（自然科学版）》2016年第7期2432-2440,共9页Journal of Central South University:Science and Technology

基　　金：国家自然科学青年基金资助项目(51208516);湖南省博士生科研创新项目(CX2014B072)~~

摘　　要：基于土压平衡盾构改良渣土的力学行为直接影响着土舱压力传递性、地层沉降和开挖面稳定性,以南昌地区泥质粉砂岩和砾砂作为试验材料,采用泡沫剂和膨润土泥浆为改良剂,对渣土进行三轴快剪(不固结不排水)试验,并基于三维数值模拟,分析渣土改良对地层响应的影响。研究结果表明:改良和未改良渣土的应力-应变曲线都近似于硬化型曲线,并且硬化曲线特征不受改良剂的影响;改良后渣土的抗剪强度大幅度减小,改良剂添加率越高,渣土抗剪强度越低,改良效果越好;泡沫和膨润土泥浆对渣土的改良机理存在一定差异,采用泡沫改良渣土能降低渣土内摩擦角和黏聚力;采用膨润土泥浆改良渣土能减小渣土内摩擦角,而其黏聚力小幅度增大;考虑改良渣土和盾构机刀盘的影响时,开挖面支护应力曲线呈现出非线性,其分布受刀盘开口分布位置的影响;开挖面的支护应力和地层响应均受到渣土改良的影响,改良效果越好,开挖面支护应力越小,开挖面前方地层沉降越大;与采用膨润土泥浆改良渣土相比,采用泡沫改良渣土后开挖面支护应力较小,地层沉降较大。Considering that mechanical behavior of conditioned soils of earth pressure balance shield tunneling directly affects pressure transmission in soil tank and ground settlement and stability of work face, agillaceous siltstone and gravelly sand of Nanchang were used as test materials, soils were conditioned with foam and bentonite slurry, and undrained unconsolidated tests of conditioned soils were carried out. Based on 3-D numerical simulation, soil conditioning impact on formation response was studied. The results show that the type of stress-strain curves of conditioned and unconditioned soils is a hardening type and additives do not affect the characteristics of the curve. Compared with unconditioned soils, the strength of conditioned soils decreases greatly. Undrained shear strength gradually reduces with the increase of additive ratio, and performance of soils is also better. There are some differences between the mechanism of foam and bentonite slurry to condition soils. The internal friction angle and cohesion of conditioned soils conditioned by foam decrease. For conditioned soils conditioned by bentonite slurry, its internal friction angle decreases, and its cohesion slightly increases. In consideration of conditioning soils and cutterhead of shield machine, the supported stress curve is nonlinear, which is affected by distribution of the opening of cutterhead, when the shield machine stops to assemble segment. Soil conditioning has certain impact on the supported stress of work face and formation response. The supported stress of work face reduces and ground settlement increases when soils is conditioned. Compared to bentonite slurry, when foam is used to condition soils, the supported stress of work face is smaller and the ground settlement is greater.

关 键 词：渣土改良 应力-应变曲线 不排水抗剪强度 支护应力 地层响应 

分 类 号：U445.4[建筑科学—桥梁与隧道工程]