振杆密实法加固粉土地基效果试验
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摘要
为了评价振杆密实法加固粉土地基的效果,对宿(迁)新(沂)高速公路粉土地基采用十字形振杆密实技术进行处理,通过加固前后室内试验和原位测试分析了侧向土压力系数和超固结比等参数的变化;研究了路堤填筑期工作性状,分别基于CPTu原位测试和室内试验得到的压缩模量计算加固后上覆荷载下沉降,并与采用双曲线法基于现场实测资料的预测沉降和瑞典振动翼加固沉降进行对比,以证明基于CPTu测试的沉降计算方法的可靠性;比较加固前后相同上覆荷载下地基计算沉降量以分析地基加固前后路堤荷载作用下控制变形能力的差异;比较了加固前后场地土类别的变化。结果表明:试验场地土层加固后静止侧压力系数提高了40%,超固结比提高到1.8～2.3,出现超固结效应;十字形振杆控制粉土地基沉降效果优于瑞典振动翼,基于CPTu测试确定土压缩模量的方法能较好地预测地基沉降,在相同高度填土荷载下,加固后地基沉降比加固前减少约25%;加固后场地指数提高,特征周期减小,场地土类由软弱土提高为中软土,场地类别由Ⅳ类提高为Ⅲ类,在不影响建筑物基础抗震要求的情况下,可大幅降低建设投资。
Crisscross section vibratory probe compaction was used to reinforce a silty foundation at Suqian—Xinyi Expressway in order to investigate the compaction effect. Field and laboratory tests were conducted to analyze variation of the lateral earth pressure coefficient and the over-consolidation ratio before and after reinforcement. The properties of an embankment during filling was studied, and settlement under overburden load after reinforcement was calculated based on the compressive modulus obtained by piezocone penetration test(CPTu) and laboratory tests. These results were compared with settlement predicted by applying the hyperbolic method to measured data as well as that of Swedish vibro-wing compaction, which verified the reliability of settlement calculation based on CPTu. The calculated settlement of the foundation under the same overburden load before and after reinforcement was compared to analyze the difference in deformation control ability under embankment load. The change of site classification before and after reinforcement was also discussed. The results show that the lateral earth pressure coefficient is increased by 40%, and the over-consolidation ratio is increased to 1.8-2.3 after reinforcement; the over-consolidation effect appears in the soil layer. Therefore, the effect of crisscross section vibratory probe compaction on the settlement of a silty foundation under embankment load is better than that of Swedish vibro-wing compaction. Determining the soil compression modulus based on CPTu can also better predict foundation settlement. The foundation settlement after reinforcement is approximately 25% less than that before reinforcement under the same overburden load. After reinforcement, the site index improves, and characteristic period reduces; soil type improves from soft soil to medium soft soil; and site classification improves. Therefore, construction investment can be greatly reduced without affecting the seismic requirement of the foundation.
Crisscross section vibratory probe compaction was used to reinforce a silty foundation at Suqian—Xinyi Expressway in order to investigate the compaction effect. Field and laboratory tests were conducted to analyze variation of the lateral earth pressure coefficient and the over-consolidation ratio before and after reinforcement. The properties of an embankment during filling was studied, and settlement under overburden load after reinforcement was calculated based on the compressive modulus obtained by piezocone penetration test(CPTu) and laboratory tests. These results were compared with settlement predicted by applying the hyperbolic method to measured data as well as that of Swedish vibro-wing compaction, which verified the reliability of settlement calculation based on CPTu. The calculated settlement of the foundation under the same overburden load before and after reinforcement was compared to analyze the difference in deformation control ability under embankment load. The change of site classification before and after reinforcement was also discussed. The results show that the lateral earth pressure coefficient is increased by 40%, and the over-consolidation ratio is increased to 1.8-2.3 after reinforcement; the over-consolidation effect appears in the soil layer. Therefore, the effect of crisscross section vibratory probe compaction on the settlement of a silty foundation under embankment load is better than that of Swedish vibro-wing compaction. Determining the soil compression modulus based on CPTu can also better predict foundation settlement. The foundation settlement after reinforcement is approximately 25% less than that before reinforcement under the same overburden load. After reinforcement, the site index improves, and characteristic period reduces; soil type improves from soft soil to medium soft soil; and site classification improves. Therefore, construction investment can be greatly reduced without affecting the seismic requirement of the foundation.
引文
[1] 程远,刘松玉,杜广印.振杆密实法的应用概况与研究进展[J].地震工程学报,2015,37(增2):207-213. CHENG Yuan, LIU Song-yu, DU Guang-yin. Application and Recent Research Progress of Vibratory Probe Compaction Method [J]. China Earthquake Engineering Journal, 2015, 37 (S2): 207-213.
[2] 程远,刘松玉,蔡国军,等.基于CPTU测试的共振密实法加固可液化地基效果评价[J].东南大学学报,2011,41(5):1075-1080. CHENG Yuan, LIU Song-yu, CAI Guo-jun, et al. Assessment of Resonance Compaction Method on Soil Liquefaction Treatment Through CPTU Test [J]. Journal of Southeast University, 2011, 41 (5): 1075-1080.
[3] CHENG Y, LIU S, LIU Z, et al. Seismic Cone Penetration Test Assessment of Vibratory Probe Compaction for Liquefaction Mitigation [C]// HRYCIW R D, ZEKKOS A A, YESILLER N. Proceedings of Geo-Congress 2012. Reston: ASCE, 2012: 1898-1907.
[4] CHENG Y, LIU Z, LIU S, et al. Investigation of Vibratory Compaction Effect: A Case Study in China [C]// COUTINHO R Q, MAYNE P W. Proceedings of 4th International Conference on Site Characterization. London: Taylor and Francis, 2013: 1493-1498.
[5] CHENG Y, ZHU H, JING F, et al. Experimental Research of Spatial Variation of Compaction Effect on Vibratory Probe Compaction Method for Ground Improvement [J].Procedeia Engineering, 2017, 189: 466-471.
[6] MASSARSCH K R, FELLENIUS B H. Vibratory Compaction of Coarse-grained Soils [J].Canadian Geotechnical Journal, 2002, 39 (3): 695-709.
[7] MASSARSCH K R. Effects of Vibratory Compaction [C]// HOLEYMAN A, VAN DEN BERGHE J F, CHARUE N. Proceedings of Vibratory Pile Driving and Deep Soil Compaction-TRANSVIB 2002.Rotterdam: Balkema A A, 2002: 33-42.
[8] 刘松玉,程远.共振法加固公路可液化地基试验[J].中国公路学报,2012,25(6):24-29. LIU Song-yu, CHENG Yuan. Resonance Compaction Method for Highway Ground Improvement at Liquefaction Site [J]. China Journal of Highway and Transport, 2012, 25 (6): 24-29.
[9] 程远,刘松玉,朱合华,等.振杆密实法加固液化地基施工扰动与影响因素试验[J].中国公路学报,2016,29(9):38-44. CHENG Yuan, LIU Song-yu, ZHU He-hua, et al. Experiment of Construction Disturbance and Factors Influencing Vibratory Probe Compaction Effect on Liquefaction Site Treatment [J]. China Journal of Highway and Transport, 2016, 29 (9): 38-44.
[10] MASSARSCH K R, FELLENIUS B H. Deep Vibratory Compaction of Granular Soils [C]//INDRANATNA B, JIAN C. Proceedings of Ground Improvement-Case Histories. Amsterdam: Elsevier Publishers, 2005: 539-561.
[11] GB 50007—2011, 建筑地基基础设计规范[S]. GB 50007—2011, Code for Design of Building Foundation [S].
[12] SENNESET K, SANDVEN R, JANBU N. Evaluation of Soil Parameters from Piezocone Tests [J]. Transportation Research Record, 1989, 1235: 24-37.
[13] MASSARSCH K R. Settlement Analysis of Compacted Granular Fill [C]// ICSMFE. Proceedings of the 13th International Conference on Soil Mechanics and Foundation Engineering. Rotterdam: Balkema A A,1994: 325-328
[14] MASSARSCH K R, WESTERBERG E, BROMS B B. Footings Supported on Settlement-Reducing Vibrated Soil Nails [C]// ICSMFE. Proceedings of the 14th International Conference on Soil Mechanics and Foundation Engineering. Rotterdam: Balkema A A, 1997: 1533-1539.
[15] GB 50011—2010, 建筑抗震设计规范[S]. GB 50011—2010, Code for Seismic Design of Buildings [S].
[16] 程远,刘松玉.共振密实法加固可液化地基的应用研究[J].岩土工程学报,2013,35(增2):83-87. CHENG Yuan, LIU Song-yu. Application of Resonant Vibro-compaction in Treatment of Liquefiable Sites [J]. Chinese Journal of Geotechnical Engineering, 2013, 35 (S2): 83-87.
[17] 朱云鹤,周广如,赵建军.宿迁新城区地质缺陷分析与基础类型探讨[J].岩土工程学报,2000,22(2): 247-250. ZHU Yun-he, ZHOU Guang-ru, ZHAO Jian-jun. Analysis on Geological Defect and Foundation Type in the New Urban Area of Suqian City, Jiangsu Province [J].Chinese Journal of Geotechnical Engineering, 2000, 22 (2): 247-250.
[2] 程远,刘松玉,蔡国军,等.基于CPTU测试的共振密实法加固可液化地基效果评价[J].东南大学学报,2011,41(5):1075-1080. CHENG Yuan, LIU Song-yu, CAI Guo-jun, et al. Assessment of Resonance Compaction Method on Soil Liquefaction Treatment Through CPTU Test [J]. Journal of Southeast University, 2011, 41 (5): 1075-1080.
[3] CHENG Y, LIU S, LIU Z, et al. Seismic Cone Penetration Test Assessment of Vibratory Probe Compaction for Liquefaction Mitigation [C]// HRYCIW R D, ZEKKOS A A, YESILLER N. Proceedings of Geo-Congress 2012. Reston: ASCE, 2012: 1898-1907.
[4] CHENG Y, LIU Z, LIU S, et al. Investigation of Vibratory Compaction Effect: A Case Study in China [C]// COUTINHO R Q, MAYNE P W. Proceedings of 4th International Conference on Site Characterization. London: Taylor and Francis, 2013: 1493-1498.
[5] CHENG Y, ZHU H, JING F, et al. Experimental Research of Spatial Variation of Compaction Effect on Vibratory Probe Compaction Method for Ground Improvement [J].Procedeia Engineering, 2017, 189: 466-471.
[6] MASSARSCH K R, FELLENIUS B H. Vibratory Compaction of Coarse-grained Soils [J].Canadian Geotechnical Journal, 2002, 39 (3): 695-709.
[7] MASSARSCH K R. Effects of Vibratory Compaction [C]// HOLEYMAN A, VAN DEN BERGHE J F, CHARUE N. Proceedings of Vibratory Pile Driving and Deep Soil Compaction-TRANSVIB 2002.Rotterdam: Balkema A A, 2002: 33-42.
[8] 刘松玉,程远.共振法加固公路可液化地基试验[J].中国公路学报,2012,25(6):24-29. LIU Song-yu, CHENG Yuan. Resonance Compaction Method for Highway Ground Improvement at Liquefaction Site [J]. China Journal of Highway and Transport, 2012, 25 (6): 24-29.
[9] 程远,刘松玉,朱合华,等.振杆密实法加固液化地基施工扰动与影响因素试验[J].中国公路学报,2016,29(9):38-44. CHENG Yuan, LIU Song-yu, ZHU He-hua, et al. Experiment of Construction Disturbance and Factors Influencing Vibratory Probe Compaction Effect on Liquefaction Site Treatment [J]. China Journal of Highway and Transport, 2016, 29 (9): 38-44.
[10] MASSARSCH K R, FELLENIUS B H. Deep Vibratory Compaction of Granular Soils [C]//INDRANATNA B, JIAN C. Proceedings of Ground Improvement-Case Histories. Amsterdam: Elsevier Publishers, 2005: 539-561.
[11] GB 50007—2011, 建筑地基基础设计规范[S]. GB 50007—2011, Code for Design of Building Foundation [S].
[12] SENNESET K, SANDVEN R, JANBU N. Evaluation of Soil Parameters from Piezocone Tests [J]. Transportation Research Record, 1989, 1235: 24-37.
[13] MASSARSCH K R. Settlement Analysis of Compacted Granular Fill [C]// ICSMFE. Proceedings of the 13th International Conference on Soil Mechanics and Foundation Engineering. Rotterdam: Balkema A A,1994: 325-328
[14] MASSARSCH K R, WESTERBERG E, BROMS B B. Footings Supported on Settlement-Reducing Vibrated Soil Nails [C]// ICSMFE. Proceedings of the 14th International Conference on Soil Mechanics and Foundation Engineering. Rotterdam: Balkema A A, 1997: 1533-1539.
[15] GB 50011—2010, 建筑抗震设计规范[S]. GB 50011—2010, Code for Seismic Design of Buildings [S].
[16] 程远,刘松玉.共振密实法加固可液化地基的应用研究[J].岩土工程学报,2013,35(增2):83-87. CHENG Yuan, LIU Song-yu. Application of Resonant Vibro-compaction in Treatment of Liquefiable Sites [J]. Chinese Journal of Geotechnical Engineering, 2013, 35 (S2): 83-87.
[17] 朱云鹤,周广如,赵建军.宿迁新城区地质缺陷分析与基础类型探讨[J].岩土工程学报,2000,22(2): 247-250. ZHU Yun-he, ZHOU Guang-ru, ZHAO Jian-jun. Analysis on Geological Defect and Foundation Type in the New Urban Area of Suqian City, Jiangsu Province [J].Chinese Journal of Geotechnical Engineering, 2000, 22 (2): 247-250.