为确定MJS+水平冻结法联合加固的冻结开冻时机，对MJS加固水泥土试验桩水化放热规律进行研究。采用直接法测定水泥水化热获得不同水泥质量掺量（40%、45%、50%、60%、70%）的水化热和水化放热速率，利用水化热室内试验所得数据进行数值模拟预测MJS加固体温度场变化规律，并结合现场MJS试验桩温度实测数据进行对比分析。结果表明： 1）MJS水泥土试验桩的中心温度随水泥质量掺入比增大而提高； 2）试验桩温度模拟值与实测值变化趋势相近，验证了数值模拟的正确性； 3）MJS水泥土试验桩的中心温度先升高后缓慢降低，5 d左右水化放热量达到峰值，温度为56.1~69.2 ℃，水泥土水化放热随水泥质量掺入比的增大而升高； 4）大体积水泥土因水化作用中心温度上升较大，单桩MJS水泥水化热在施工后30 d基本释放完成，故宜在30 d后进行人工冻结加固。
To determine the freezing starting time of the
combination reinforcement of the metro jet system(MJS) and horizontal freezing
method, the hydration heatrelease law of a MJSreinforced cementsoil test pile is studied.
The hydration heat and hydration heatrelease rate of
the cementsoil pile with different cement contents
(40%, 45%, 50%, 60%, and 70%) are measured using a direct method. Finally,
numerical simulations are performed to predict the variation law of the MJS
reinforcement temperature field using the data obtained from the hydration heat
laboratory tests. A comparative analysis of the simulated prediction and the
measured temperature of the MJS test pile from the field is performed. The
results reveal the following. (1)The central temperature of the MJS cementsoil test pile increases with the increasing of cementmixing ratio. (2) The change trends of the simulated and measured
temperatures of the test pile are similar, validating the numerical simulation.
(3) The central temperature of the MJS cementsoil test
pile first increases and then decreases gradually; the hydration heatrelease peaks in approximately five days, reaching 56.1~69.2 ℃. Thus, the hydration heat release of the cementsoil pile increases with the increasing of cementmixing ratio. (4) The temperature at the center of the large volume
of the cementsoil pile increases due to the hydration
effect. The hydration heat release of the MJS cementsoil
test pile stops 30 days after construction, indicating that artificial freezing reinforcement can be
conducted.
