水下岩溶浆液抗分散性质试验研究及工程应用

开发了一种水下岩溶注浆材料抗分散性质测试装置,能科学评价注浆浆液的抗分散性质。利用该装置进行了改性黏土水泥膏浆充填水下岩溶的抗分散性质试验,采用留存率指标对浆液在不同水固比、岩溶水流速下的抗分散性质进行了定量评价,并对留存体进行物理力学性能测试。试验表明,改性黏土水泥膏浆抗分散性能受浆液水固比、岩溶充填物及岩溶水流速等因素影响明显,在不大于0.8 m/s的岩溶水流速下浆液抗分散性能良好,随着浆液水固比或岩溶水流速的减小,浆液留存率呈增大趋势,而充填物的存在会显著提高浆液的留存率。取留存体进行物理力学性能测试,留存体密实度受充填物影响较大,浆液水固比次之,岩溶水流速影响较小;动水岩溶环境下注浆时,浆液顺水扩散距离大于逆水扩散距离,浆液黏度对扩散距离影响明显,岩溶水流速有利于浆液沿顺水流方向扩散而抑制浆液沿逆水流方向扩散;留存体28 d抗压强度受抗冲条件影响明显,影响因素中充填物对留存体的抗压强度影响最大,其次为浆液水固比和岩溶水流速,岩溶水养护环境下28 d抗压强度明显小于淡水环境养护,但仍可达3 MPa。经工程应用原型试验表明,改性黏土水泥膏浆可用于一定岩溶水流速下的岩溶区治理,室内试验提出的水下岩溶治理工程浆液配比选取原则可行,可为盾构隧道水下岩溶注浆治理提供理论指导。

Experimental study and engineering application of anti-washout properties of underwater karst grout

The test apparatus for underwater karst grouting materials, which be used to evaluate the anti-washout properties of grout, is developed. Using this device, a series of anti-washout property tests on modified clay cement paste grout in underwater karst fillings are conducted. The retention ratio index of grout is utilized for the quantitative evaluation of the anti-washout properties of grout, and the tests on physical and mechanical properties of retained body are also carried out. The result shows that the anti-washout properties of modified clay cement paste grout are greatly affected by the water cement ratio of grout, karst fillings and velocity of water flow. The anti-washout properties of grout are relatively good when the velocity of karst water flow is no more than 0.8 m/s. With the increasing water cement ratio of grout or the decreasing water flow velocity, the retention ratio of grout tends to increase and can be significantly improved with the existence of karst filling materials. The physical and mechanical performance tests on the retained body indicate that the density is greatly influenced by the filling materials. When grouting under hydrodynamic environment, the downstream grout diffusion distance is greater than the upstream one. The viscosity of grout has a great effect on the diffusion distance, and the velocity of karst water flow can be in favour of the diffusion of grout along the water flow direction and restrain the diffusion along the reverse water flow direction. The 28-d compressive strength of retained body is deeply influenced by filling materials. The 28-d compressive strength under karst water condition is significantly less than that under freshwater condition, but it is still up to 3 MPa. The engineering application of prototype tests indicates that the modified clay cement paste grout can be used for treatment of karst areas under certain velocities of karst water. The formula for grout in underwater karst treatment derived by indoor tests is feasible and may provide theoretical guidance for underwater karst grouting of shield tunnels.