摘要
高压旋喷桩法是加固高灵敏软土地基的主要方法之一。现有的试验与理论研究中关于冒浆高度对加固效果影响的研究较为缺乏,为高压旋喷桩的设计及施工带来了不确定性。本文以浙能六横电厂新建盾构隧道工程为依托,结合单桩竖向载荷试验、复合地基载荷试验、取芯试验、桩顶土方开挖试验等原位试验,研究了高压旋喷桩处理后高灵敏软土地基的承载特性与强度。试验结果表明,旋喷桩最大冒浆高度为2.0 m,冒浆体近地表部分强度不高。冒浆高度为0.5 m时水泥土强度明显提高。可能的原因是过高的注浆压力过度扰动高灵敏软土地基,导致土体结构性过度丧失。旋喷桩处理后,单桩极限承载力为250 kN,复合地基承载力为89 kPa,由于土层灵敏度较高,施工时难以控制冒浆量,地基承载力低于设计值,在实际工程施工时应考虑其影响。
The high pressure jet grouting pile method is one of the main methods of strengthening very sensitive soft soil foundations.In the existing experimental and theoretical studies,there is a lack of research on the influence of the height of grouting on the reinforcement effect,which brings about uncertainties in the design and construction of high-pressure jet grouting pile.For this purpose,this study presents a field study that aims to quantify the influence of amount of grouting on bearing capacity of high-pressure jet grouting piles.The field tests consist of single-pile vertical load test,composite foundation load test,coring test,and earth excavation test at the top of the pile.The test results show that the maximum grouting height of the jet grouting pile is 2.0 m.Under this circumstance,the strength of the grouting body near the surface has not been significantly improved.This may be attributed to the high grouting pressure over-disturbing the ground,leading to de-structuration of the sensitive clay.On the other hand,the strength of the cement soil is well improved when the grouting height is 0.5 m.The ultimate bearing capacities of single pile and the composite foundation are 250 kN and 89 kPa,respectively.Due to the high sensitivity of the clay,it is difficult to control the amount of grouting during construction,and the bearing capacity of foundation is lower than the design value.Therefore,its influence should be considered in engineering construction.
作者
潘华林
钱和平
蔡泽恩
兰燕
郭轩恺
洪义
PAN Hua-lin;QIAN He-ping;CAI Ze-en;LAN Yan;GUO Xuan-kai;HONG Yi(Zhejiang Provincial Energy Group Co.,Ltd.,Hangzhou 310007,China;College of Engineering and Architecture,Zhejiang University Hangzhou 310058,China)
出处
《地基处理》
2021年第1期71-75,共5页
Journal of Ground Improvement
基金
国家重点研发计划(2016YFC0800200)
国家自然科学基金(51779221)
国家自然科学基金(51939010)。
关键词
高压旋喷桩
高灵敏软土
承载力
原位试验
冒浆高度
high pressure jet grouting pile
highly sensitive soft soil
bearing capacity
in-situ testing
amount of grouting
