砂卵石地层是一种典型的力学不稳定地层，由卵石骨架和填充的砂层组成，流塑性差、无黏聚力、孔隙率较大。为保障土压平衡盾构在富水砂卵石地层施工过程中渣土顺利排出，防止部分区间可能出现的涌水、喷泥等问题，以洛阳轨道交通1号线青年宫站—夹马营站区间为依托工程，通过黏度试验测试浆液是否满足工程泵送要求，随后采用膨润土和羧甲基纤维素混合泥浆对富水砂卵石地层进行渗透、坍落度等渣土改良试验，根据渣土改良效果提出建议配合比。试验结果表明联合使用钠基膨润土-羧甲基纤维素的配比方案，能够较为有效地改善砂卵石地层渣土和易性，也能够很好地预防土压平衡盾构施工过程中可能出现的涌水、涌砂问题。

Sand and pebble stratum is a typical mechanically unstable stratum, which is composed of a pebble skeleton and a filled sand layer, with poor plasticity, no cohesion, and larger porosity. In order to ensure the smoothly discharge of the muck and to prevent water inrush and mud spraying problems that may occur in some sections during the construction of the earth pressure balance shield in the waterrich sand and pebble stratum. Taking Luoyang Rail Transit Line 1 Qingniangong Station to Jiamaying Station as the engineering background, the viscosity test is used to test whether the slurry meets engineering pumping requirements. Then tests of permeation and slump are carried out to test the effect of bentonite and carboxymethyl cellulose(CMC) mixed mud on waterrich sand and pebble formations. The suggested mixing ratio was proposed according to the results of the improvement of the mud. The test results show that the combination of sodium bentonite and CMC can effectively improve the workability of the sandy pebble stratum residue，and it can also prevent water and sand inrush problems that may occur during the construction of the earth pressure balance shield.