水平旋喷桩施工期间，大量高压流体注入土层，引起土层内部产生较大的膨胀作用，致使周围一定区域的土体发生变形。水平旋喷桩施工引起土体变形可以归结为压力膨胀和体积膨胀共同作用的问题。依托单根水平旋喷桩施工的现场实例，建立了水平旋喷桩施工引起土体变形的数值模型。将水平旋喷桩施工引起的土体变形问题简化为圆孔的膨胀问题，可以统筹考虑注浆压力和注浆流量的影响。首先需要确定注浆压力的影响半径和注浆流量引起的体积膨胀比，然后可以通过数值模型计算膨胀引起的土体变形。数值分析结果与现场实测值的对比表明，当注浆压力影响半径为成桩半径的6倍时，数值计算结果与现场实测值吻合较好。

During the installation of horizontal jet grout columns, the high pressurized fluids injected into the soil can induce the expansion of the foundation soils, causing significant movements of the soils around jet grouting locations. The soil deformation caused by installation of horizontal jet grout columns can be considered as the combined effects of the expansions induced by the high pressure and the volume of fluid. Based on a case history of the construction of horizontal jet grout column, a finite element model is developed for analysing the soil deformation caused by installation of horizontal jet grout columns. In this model, the soil deformation caused by installation of horizontal jet grout columns is simplified as the expansion of a round hole, the jetting pressure and the volume of injected fluids can be considered as a whole. A method is proposed to estimate the influencing radius of the jetting pressure, and the equations for determining the ratio of volume expansion are provided. Based on these, the soil deformation can be obtained by the finite element analysis. Comparisons of the measured values and numerical results indicate that the numerical results are in good agreement with the measured data when the influencing radius is 6 times that of the column, demonstrating the applicability of the developed finite element model.