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为模拟土体加卸荷对桩基摩阻力产生的影响,研制了土体加卸荷对桩基影响模拟试验系统。该系统包括加卸荷系统、模型桩、量测系统及数据自动采集系统4个子系统。该系统可通过气压加载法在大直径土样顶面以较高荷载进行加卸荷,模拟不同土性、不同桩端约束条件下土体沉降或回弹对模型桩产生的影响,并通过试验验证了其有效性和可靠性。试验表明,系统智能化程度高,可实现大荷载长期稳压,量测系统灵敏度高稳定性好;不同桩端约束条件对桩侧摩阻力分布影响很大;土样在卸荷比达到约0.8发生强回弹,但对桩端嵌固条件下桩顶2/3桩长范围和桩端自由条件下全桩长桩侧摩阻力影响不明显。系统可用于模拟桩间土大面积均匀加卸荷对工程桩的影响。
In order to simulate the influence of soil loading and unloading on the frictional resistance of pile foundation, a simulation test system for the effect of soil loading and unloading on pile foundation was developed. The system includes loading and unloading system, model pile, measuring system and automatic data acquisition system 4 subsystems. The system can be loaded and unloaded by high pressure loading on the top surface of large diameter soil by air pressure loading method to simulate the influence of soil settlement or rebound on the model pile under different earth conditions and different pile end constraints. Verify its effectiveness and reliability. The tests show that the system has a high degree of intelligence, long-term voltage regulation can be achieved with large loads, and the sensitivity and stability of the measurement system are good. The restraints of different pile ends have a great influence on the distribution of frictional resistance of the pile. When the unloading ratio reaches about 0.8 Strong rebound occurred, but the influence of pile length on pile side long pile friction under 2/3 pile length and pile end condition was not obvious. The system can be used to simulate the impact of large area uniform loading and unloading on the pile.