Top structure and basement will confront the risk of being damaged on account of large stress and strain fields incurred by differential uplift and settlement between inner column and diaphragm wall in top-down method...Top structure and basement will confront the risk of being damaged on account of large stress and strain fields incurred by differential uplift and settlement between inner column and diaphragm wall in top-down method. Top-down excavation of the Metro Line 10 in Shanghai was modeled with finite element analysis software ABAQUS and parameters of subsoil were obtained by inverse analysis. Based on the finite element model and parameters, changes in the following factors were made to find more effective methods to restrain differential uplift and settlement: length of diaphragm wall, thickness of jet-grouting reinforcement layer, ways of subsoil reinforcement, sequence of pit excavation, connection between slabs and diaphragm wall or column and width of pit. Several significant results are acquired. The longer the diaphragm wall is, the greater the differential uplift between column and diaphragm wall is. Rigidity of roof slab is in general not strong enough to keep diaphragm wall and column undergoing the same uplift during excavation; Uplift at head of column and differential uplift between column and diaphragm wall decrease when subsoil from-16.6 to-43 m in pit is reinforced through jet-grouting. But, as excavation proceeds to a lower level, benefit from soil reinforcement diminishes. During the process applying vertical load, the larger the depth of diaphragm wall is, the smaller the settlement is at head of column and diaphragm wall, and the greater the differential settlement is between column and diaphragm wall. When friction connection is implemented between column, diaphragm wall and floor slabs, uplifts at head of column and diaphragm wall are larger than those of the case when tie connection is implemented, and so does differential uplift between column and diaphragm wall. The maximum deflection of diaphragm wall decreases by 58% on account of soil reinforcement in pit. The maximum deflection of diaphragm wall decreases by 61.2% when friction connection is implemented instead of tie connection.展开更多
目的探讨新生儿经下肢静脉置入经外周静脉穿刺中心静脉置管(peripherally inserted central catheter,PICC)导管长度的测量方法。方法 2015年3月至2016年12月便利抽样选取东南大学附属中大医院125例行PICC置管的新生儿,随机分为观察组...目的探讨新生儿经下肢静脉置入经外周静脉穿刺中心静脉置管(peripherally inserted central catheter,PICC)导管长度的测量方法。方法 2015年3月至2016年12月便利抽样选取东南大学附属中大医院125例行PICC置管的新生儿,随机分为观察组和对照组。观察组测量时,患儿的下肢呈自然屈曲位,测量从穿刺点-腘窝静脉-股静脉-剑突软骨的长度。对照组测量时,患儿下肢伸直,测量从穿刺点-腹股沟-剑突软骨的长度。置管成功后,采用胸部X线定位比较两组测量方法的准确性。结果观察组PICC置入最佳位置成功率为80.5%,高于对照组的55.2%,差异有统计学意义(χ~2=9.36,P<0.05)。结论新生儿经下肢PICC置管,采用自然屈曲位测量,长度更为准确,可提高导管尖端一次性到位的成功率,确保PICC置管的使用安全。展开更多
基金Projects(51208071,51108312) supported by the National Natural Science Foundation of China
文摘Top structure and basement will confront the risk of being damaged on account of large stress and strain fields incurred by differential uplift and settlement between inner column and diaphragm wall in top-down method. Top-down excavation of the Metro Line 10 in Shanghai was modeled with finite element analysis software ABAQUS and parameters of subsoil were obtained by inverse analysis. Based on the finite element model and parameters, changes in the following factors were made to find more effective methods to restrain differential uplift and settlement: length of diaphragm wall, thickness of jet-grouting reinforcement layer, ways of subsoil reinforcement, sequence of pit excavation, connection between slabs and diaphragm wall or column and width of pit. Several significant results are acquired. The longer the diaphragm wall is, the greater the differential uplift between column and diaphragm wall is. Rigidity of roof slab is in general not strong enough to keep diaphragm wall and column undergoing the same uplift during excavation; Uplift at head of column and differential uplift between column and diaphragm wall decrease when subsoil from-16.6 to-43 m in pit is reinforced through jet-grouting. But, as excavation proceeds to a lower level, benefit from soil reinforcement diminishes. During the process applying vertical load, the larger the depth of diaphragm wall is, the smaller the settlement is at head of column and diaphragm wall, and the greater the differential settlement is between column and diaphragm wall. When friction connection is implemented between column, diaphragm wall and floor slabs, uplifts at head of column and diaphragm wall are larger than those of the case when tie connection is implemented, and so does differential uplift between column and diaphragm wall. The maximum deflection of diaphragm wall decreases by 58% on account of soil reinforcement in pit. The maximum deflection of diaphragm wall decreases by 61.2% when friction connection is implemented instead of tie connection.
文摘目的探讨新生儿经下肢静脉置入经外周静脉穿刺中心静脉置管(peripherally inserted central catheter,PICC)导管长度的测量方法。方法 2015年3月至2016年12月便利抽样选取东南大学附属中大医院125例行PICC置管的新生儿,随机分为观察组和对照组。观察组测量时,患儿的下肢呈自然屈曲位,测量从穿刺点-腘窝静脉-股静脉-剑突软骨的长度。对照组测量时,患儿下肢伸直,测量从穿刺点-腹股沟-剑突软骨的长度。置管成功后,采用胸部X线定位比较两组测量方法的准确性。结果观察组PICC置入最佳位置成功率为80.5%,高于对照组的55.2%,差异有统计学意义(χ~2=9.36,P<0.05)。结论新生儿经下肢PICC置管,采用自然屈曲位测量,长度更为准确,可提高导管尖端一次性到位的成功率,确保PICC置管的使用安全。
