The Monitor Measuring of Highway Tunnel in Natm

It is important that monitor measuring is applied in tunnel in regard to NATM. The monitor measuring of NATM was studied in the Fengmeiya Tunnel in Chongzun Express. Based on the regularity and conditions of the surrounding rock deformation of monitor measuring in site, the optimum time for primary and permanent support are obtained which averting successfully accidents in construction, enhancing the construction qualities and guidance to tunnel construction in Karst areas.     

Practice of Convergence Displacement Measurement of Surrounding Rock in Tongyu Tunnel

Tongyu tunnel has the following characteristicsuch as complex geological condition, deep depth, frequent water in flow, rock burst , high stress, etc., which seriously threaten the construction safety. In the tunnel construction, monitoring measurement is adopted strictly, especially for the convergence displacement measurement, and these data is processed in time to be turn back to the construction, then the stabilizationof the surroundingrock after being opened is known and the right measurement will be taken. The authors mainly introduce convergencedisplacementmeasurement technologyof the surrounding rocksand the theoryof data regression analysein the Tongyu Tunnel. the measurement result in Tongyu tunnel is shown, and it is expected to be reference to the similar engineer in future.     

Rock Deformation, Stability Monitor Active Control About Excavation of Super-span Tunnel

According to the measurement during excavation of Jinzhou tunnel with four lanes in one cave which lies on the rebuilt highway from Shenyang to Dalian, this paper analyzes the rock deformation rule, discusses the reason of instability after a highway tunnel was excavated, emphasizes the necessity of the construction stability monitor and active control. The importance of support is Fresented with bolts and shotcrete to improve and enhance the carrying capability of the rock. It is necessary to insist on the rule of measurement and active control to ensure the safety and quality of tunnel construction.     

节理岩体中连拱隧道施工对周边建筑物的影响

以重庆东水门大桥—千厮门大桥渝中区连接隧道为研究对象,基于UDEC软件建立离散元数值模拟分析模型,研究了城区连拱隧道施工引起的地表沉降,上部建筑物基础沉降及倾斜,新建隧道下方已有轨道六号线的变形、受力特征,并将监测数据与数值模拟进行对比分析。结果表明,连拱隧道左侧隧道上导坑施工引起的隧道拱顶沉降和基础沉降量最大,经计算上部建筑物基础最大沉降量为3.81 mm,最大倾斜量为0.02%,建筑物基础沉降量和倾斜在规范许可范围之内;隧道施工引起的地层损失使得轨道六号线左拱肩向上隆起,六号线弯矩分布规律和其变形形态基本一致,弯矩最大值位于左拱肩部位,最大值为238 kN·m;数值模拟计算结果与监测数据量值相当,变形趋势基本一致;采用UDEC软件可以准确地计算出隧道开挖过程中节理的存在对隧道周围建筑物变形的影响。     

Kolmogorov entropy analysis of surrounding rock system in the processing of unloading for deep buried tunnels

Rock is a kind of physical nonlinear complicated medium, under deep buried condition the surrounding rock system deformation shows geometrical nonlinear characteristic, and the interaction between the two nonlinear mechanism makes the unloading of surrounding rock system evolving complexly. Based on the Lagrangian method and large deformation caculation method, both the double nonlinearity and nonlinear dynamics character of deep buried tunnel surrounding rock system under unloading are studied. The numerical model results show that the Kolmogorov entropy has been extracted from the evolution data in the unloading process of surrounding rock system. The analysis indicates that the typical chaos character has been demonstrated in the process of unloading for deep buried tunnel surrounding system and the rock mass energy dissipation is analyzed at the stage of unloading.     

Load Calculation Method of Shallow Tunnel under Unsymmetrical Loadings in Broken Surrounding Rock

Tunnel portal section mostly faces unfavorable geologic and topographical conditions, such as broken surrounding rock, shallow and unsymmetrical loadings. The current Chinese code for design of road tunnel provides the load calculation method of tunnel under unsymmetrical. However, according to the mechanic and deformation characteristics of the tunnel lining on site, the assumption is not suitable for the shallow tunnel under unsymmetrical loadings in broken surrounding rock. Therefore, through engineering case analysis and results of three-dimensional numerical analysis, the failure mechanism of shallow tunnel under unsymmetrical loadings in broken surrounding rock is presented firstly, that is, deep buried side broken surrounding rocks slump down after excavation and squeeze the lining, which makes the lining deform outward and bear passive earth pressure. Through the failure mechanism, the surrounding rock mainly includes slumping area and passive area. Then the corresponding formulas are deduced based on limit equilibrium theory. Finally, a case study is adopted to verify the feasibility of the new method. It is show that the new method is more reasonable than the method of current code.     

Testing and modeling studies on creep characters of supports for tunnel using nonlinear constitutive model

Creep characters of tunnel supports structure is analyzed according to triaxial creep test of concrete specimen of deep tunnel supports structure adopting MTS815 hydraulic servo system. The creep parameters of nonlinear creep model are presented based oncreep curve. The finite element numerical model has been established considering tunnel construction process, creep characters of surrounding rock and support structure. The displacement characteristics, the effective stress and the maximum shear stress in different position in primary support and second lining are obtained through creep characters analysis of surrounding rock and supports structure. The features of displacement and stress dependent time of tunnel supports has visible difference comparing with discard creep effect and calculation displacement and practical monitoring results is basic concordance. The creep characters of surrounding rock and tunnel supports should be considered for deep tunnel.     

Study of Intellegent Mehod on the Tunnel Supporting Time

As an useful perspective,the NATM has gone into many hands of the tunnel and underground structure designs and constructions.But the supporting time,which determines the tunnel's support quality,is usually determined by the engineer's experience.What's more,different engineers have different decisions on the supporting time,so the construction project quality would vary greatly.In this thesis the neuro-fuzzy inferential system was set up to gain the supporting time,which can make a good use of the experience of the engineering projects.The result suggests that this system has a good accuracy and is useful in the engineering practice.     

The Method on Surrounding Rock Classification for Highway Tunnel Construction Period in The Karst Areas of South China

Through the statistical analysis of analyzed the particularity of karst surrounding rock classification, finally obtained the rock classification index system of south karst highway tunnel construction based on rock strength, rock complete coefficient ,groundwater state, structural plane state the structural plane strike to tunnel influence, karst development to tunnel influence. And the model is applied to tianshengqiao tunnel and guanshang 2 tunnel with the example verification, and compared with the classification results and experts judgment to get the accuracy is 93.3%.     

Reasonable Smooth Blasting Factor Used in Tunnel

The fact of tunnel smooth blasting is those reduce over break and minimize fracturing of the rock at the boundary of an excavation. The select ruler and assured method of smooth blasting parameter are discussed, and the quality check standard of the smooth blasting, based on the under and over-break (5~15 mm), the circumferential hole mark ratio (>50%) and rock fragment, are found. A good benefit is gotten as these used in one tunnel.     

Study of Tunnel Supporting Effect

Based on the elastic theory, an analysis can be made on stress and plastic deformation under tunnel excavation and shotcrete support.FLAC 3D can be used to simulate the mechanical behavior of excavation and support, getting the deformation of surrounding rock stress and plastic without support and shotcrete. The results show that, the prestress applied on the anchor equals to the supporting force when the tunnel plastic zone disappears. This support improves the self bearing capacity of surrounding rock, effectively suppresses the expansion of the plastic zone after the tunnel excavation, and prevents further damage to the tunnel surrounding rock.     

Elastic-Perfectly Plastic Solution of Tunnel Surrounding Rocks Using Mogi-Coulomb Strength Criterion

Reasonable choice of rock strength criteria is crucial for stress and displacement prediction and support design in tunnel engineering. Based on Mogi-Coulomb strength criterion and elastic-perfectly plastic model, analytical solutions of stress and displacement for surrounding rocks around a circular tunnel were derived The intermediate principal stress coefficient was used to present the intermediate principal stress effect. The results in this study were compared with the current solutions in the literatures and the influence of intermediate principal stress and shear strength parameters of surrounding rocks was discussed. The results showed extensive applicability and the Mohr-Coulomb strength criterion and Matsuoka-Nakai criterion are two special cases; when the intermediate principal stress coefficient b was equals to 0.5, the results indicated that the intermediate principal stress effect and its range for rock strength; the influence of cohesion and internal friction angle on the plastic radius and tunnel wall displacement was significant; Care should be taken to the effects of intermediate principal stress and shear strength parameter variations of surrounding rocks on tunnel design and construction.     

Finite Element Analysis on Interaction of Neighboring Highway Tunnels under Construction

Recently, the construction of neighboring highway tunnels with small interval gets more and more in China. The construction of such tunnels proceeds usually by excavating one after another. The second tunnel is constructed with the surrounding rock disturbed by the first one. And the construction of second tunnel also has effect on the first excavated one. For revealing the interaction laws of such tunnel construction in combination with the engineering practice of Lanfeng tunnel at Jinshan Road in Chongqing, The FE numerical simulation analysis was used to study the characters of surrounding rock deformation, stress field, and plastic zone of the tunnel. From this analysis, it clearly shows that the excavation of second tunnel has significant influence on the first one. This study provides a scientific basis for design and excavation of neighboring highway tunnels.     

Analysis of Seismic Dynamic Responses of Tunnel throughFault Zone in High Earthquake Intensity Area

Based on dynamic time history analysis, dynamic response behavior of an un supported tunnel through fault zone which was simulated by interface and solid elements was studied under uniform input earthquake wave excitation. The analyses of response behaviors, including displacement difference, acceleration magnification, and plastic zones and so on, were carried out when earthquake wave excitation was input along transverse, longitudinal and vertical of tunnel respectively. The results show that simulation method for fault zone is effective; the earthquake causes obvious displacement difference at fault zone and surrounding rock contacting part. The maximal displacement difference reaches to 51.8mm under transverse uniform input earthquake wave excitation. And the displacement difference under vertical and longitudinal is only 44.3% and 23.1% of the transverse value, respectively; the acceleration magnification in fault zone is significantly greater than that in surrounding rock. Shear failure zone appears at the fault zone and surrounding rock contacting part, and it is especially prominent under input longitudinal earthquake wave excitation. It is proposed that fault zone has significantly influence on the dynamic performance of tunnel. The fault zone and the transitional zones are the control zones of seismic design when tunnel passes through fault zone, thus, the study on the anti seismic measures should be further strengthened.     

Analysis of Solid Fluid Coupling for Tunnel Excavation in Complicated Fractured Rock Masses

When tunnels are through water bearing section of fractured rock mass, a complex interaction process between rock mass deformation and fluid transportation is one of the most important reasons for water gushing, water bursting and mud bursting.To study the rock mass deformation and fluid transportation in tunnel excavation under complex geological conditions, a hydraulic model of complex crack rock mass was established from the relationship between the crack growth degree of surrounding rock in deep buried tunnel and the engineering scale, with which fracture network of different levels in rock mass could be considered simultaneously.Furthermore,a computer Fortran program was put forward to simulate the solid fluid coupling of excavation process of a deep buried tunnel.And it was found that the principal fractures had strong flowing action and network fractures had storage function and lag effect in seepage area.And the yield area of surrounding rock was increased under the coupling of seepage field and stress field.     

Experimental Study on Construction Method of Super-Large Section Tunnel

For the super-large section tunnel due to its super large span and flatness,together with the effect of various processes and excitation of surrounding rock during construction,the mechanical behavior of super-large section tunnel is quite complicated.Making use of the "CTSSSRH",the physical analogue for simulating the construction dynamic process of super-large section tunnel in different construction methods is experimented.The rule of surrounding rock displacement and strain development is studied and the reasonable construction method is put forward.     

MODEL TEST RESEARCH ON A COMPOSITE LINING OF UNDERGROUND ENGINEERING IN JOINTED ROCK

Combined with thedesign precept of Cai-Yuan highway tunnel 2 in Chongqing,stress state,time ffectiveness and rupture mechanism of rock near the bounda-ries of the tunnel and the second lining in jointed rock mass arc studied with model tests.The results show that shotcretc-bolt support betters mechanical properties of the periphey rock of the tunnel,and increases the capacity of anti-deformation.The second lining also has the action of supporting structure.     

Analysis on the influence from rectangle cavity behind the lining to the primary support of tunnel

In process of the tunnel construction throw New Austrian Tunnelling Method, the result of smoothwall blasting to rock tunnel is not good, there are more and more cavities produced behind the lining. On the basis of engineering project, this paper makes the three-dimensional elastic-plastic analysis throw numerical simulation, discusses the stress-strain behavior of primary support when there is a different size of rectangle cavity behind the lining. In addition the safety factor of tunnel is calculated with cavity based on the strength reduction finit element method. This factor is compared with the factor of health tunnel. The stability of tunnel structure system is estimated through the linear regression analysis between stress of lining and safety factor.     

Dynamic Construction Mechanical Behavior of a Deeply Buried Intersection Tunnel

Excavation of an intersection tunnel between independent double tunnels leads again to stress release and redistribution in the surrounding rock and the support structure of the chief tunnel, resulting in change of mechanical behavior of the rock mass an