黏土中考虑土体卸荷效应的后注浆压密模型

为研究黏土中考虑土体卸荷条件下后注浆的压密效应,基于球孔扩张理论并通过土体弹性模量折减值来考虑不同卸荷程度的影响,建立考虑土体卸荷效应影响的压密注浆模型,计算不同卸荷程度下压密注浆极限注浆压力、浆体扩张率、塑性区扩张率、径向和环向应力以及径向位移沿径向的分布关系.结果表明:压密注浆极限注浆压力以及塑性区半径随浆体扩散半径增长的速率均随土体卸荷比的增大而非线性减小；同一注浆压力下,当卸荷比小于0.8时,土体卸荷程度不同对土体内部径向应力、环向应力以及径向位移沿径向分布不产生显著影响,当卸荷比大于0.8时,注浆体周围同一位置处的土体径向应力、环向应力以及径向位移显著高于卸荷比小于0.8时的情况；同一注浆量下,相同位置处的土体径向应力,达到最小环向应力、稳定环向应力和稳定径向应力对应的径向距离均随卸荷程度的增大而减小,但是土体径向位移分布不受卸荷程度改变的影响；同一卸荷比下,相同位置处的径向应力,达到最小环向应力、稳定环向应力、稳定径向应力以及稳定径向位移对应的径向距离均随注浆量的增大而增大；最小环向应力值不受卸荷程度和注浆量改变的影响.

Compaction grouting model in clay considering unloading effect

To study the compacting effect of post-grouting in clay under unloading effect, a compaction grouting model was constructed based on the spherical cavity expansion theory and the effect of different unloading degrees through the reduction of soil elastic modulus. The ultimate grouting pressure, expansion rate of grouting, expansion rate of plastic zone, and distributions of radial and circumferential stresses and radial displacement along radial directions were calculated under different unloading degrees. Results show that the ultimate grouting pressure of compaction grouting and the increase rate of plastic zone radius with the diffusion radius of the grout decreased nonlinearly with the increase of the unloading degree. Under the same grouting pressure, when the value of unloading ratio was less than 0.8, the unloading degree had no obvious effect on the distributions of radial and circumferential stresses and radial displacement along radial directions, whereas when the value of unloading ratio was larger than 0.8, the radial and circumferential stresses and radial displacement of the soil at the same position were obviously larger than those when the unloading ratio was less than 0.8. For the same grouting volume, the radial stress at the same position, the minimum circumferential stress, and the radial distance of the steady values of circumferential and radial stresses decreased with increasing unloading degree. However, the distribution of radial displacement was not affected by the unloading degree. With the same unloading ratio, the radial stress at the same position, the minimum circumferential stress, the steady values of circumferential and radial stresses, and the radial distance of the steady values of radial displacement increased with the increase of grouting volume. The magnitude of the minimum circumferential stress was not affected by the unloading degree and grouting volume.