Lateral Horizontal Displacement Research Articles

Surgical management of Grisel syndrome in the adult patient: illustrative case.

BACKGROUNDGrisel syndrome describes an infectious soft tissue process that destabilizes the cervical bony elements and ligamentous complexes. This nontraumatic atlantoaxial rotary subluxation occurs in children primarily. This case illustrates a rare case presentation of an adult with Grisel syndrome: infectious destruction of the right atlantoaxial facet joint caused the occiput-C1 vertebra (head) to rotate rightward with lateral horizontal displacement off the C2 vertebra.OBSERVATIONSBecause the infection destroyed the C1 bony arch and atlantoaxial facet joints with epidural extension, the rotated head and atlas pulled the brainstem–cervical spinal cord junction against a fixed odontoid process, resulting in a cord contusion. Because of the highly unstable craniocervical junction, the patient presented with torticollis and left upper extremity weakness.LESSONSTreatment entailed closed reduction under general anesthesia followed by occipitocervical fusion with an occipital plate, C1 lateral mass screws, and C2-C5 pedicle screws. This case describes the unique surgical pearls necessary for occipitocervical fusion of an unstable craniocervical junction, including tips with neuronavigation, trajectories of the cervical pedicle screws, aligning the lateral mass and pedicle screws with the occipital plate, and nuances with occipitocervical distraction.

Tunnel Face Stability Study in Soft Shallow Tunnel

With Xiamen Jiaheyuan underground access as the project background, tunnel face stability of soft shallow tunnel was analyzed under the condition of no pre-reinforcement by means of three-dimensional finite element method. The results indicated that the ground was relaxed because the tensile stress appeared in front and top of tunnel face after excavation, at the same time, the ground into the plastic state around the tunnel face. From the point of view of deformation, the displacement of tunnel face were such as the longitudinal horizontal displacement reached the maximum, the vertical deposition following by, and the lateral horizontal displacement being the least. Further analysis showed that the longitudinal horizontal displacement in front of tunnel face mostly produced at 1.0D (one excavation width) distance before tunnel face, the maximum displacement was located at the center of tunnel face. The conclusions remind that engineers also pay attention to the tunnel face reinforcement in front and top of tunnel face to minimize the impact of surface environment during tunnel construction in soft shallow tunnels.

The Stability Monitoring of High Fill Soggy Railway Embankment in Chongqing Steel Plant

Based on the special section of high fill soggy embankment in Chongqing Steel Plant Railway, we successfully implemented high fill soggy embankment’s dynamic stability monitoring by laying high precision measuring instruments inside the embankment. This stability monitoring reveals the changes and rules of the lateral horizontal displacement, layered settlement, internal stress of this particular form of embankment and provides references for designing and construction for high fill soggy embankment in mountainous area.

Effect Analysis of Double-Line Parallel Shield Tunnel Crossing Frame Structure Building Based on GTS

Considering the interaction of building-soil-tunnel, the grillage beams foundation frame building vertical crossed by Double-Line (DL) parallel shield tunnel was simulated by 3D MIDAS/GTS software. The results show that: after left-shield tunnel construction had done, during the passage of the right shield tunnelling, the differential settlement decreased gradually, settlement is slightly larger than the left when the right tunnel had ready crossed the building. Uneven settlement first increases, and then decreases gradually tends to zero. Lateral horizontal displacement changes little, and longitudinal horizontal displacement first increased and then decreases. The building’s maximum first principal stress exceeds the standard value, which may cause cracking. With the increase of L the distance from frame axis to the axis of the two tunnels, the first principal stress P1 and maximum shear strain MSmax tended to reduce in general. The maximum differential settlement between columns first increased and then decreased.

Impact of Double-O-Tube Shield Tunnel Construction on Independent Foundation Frame Building

Due to its better advantages, Double-O-Tube(DOT) shield has been widely applied in shield tunnel construction. But the impact caused by shield tunnel construction on buildings hasn’t been taken seriously. Considering the interaction of building-soil-tunnel, the independent foundation frame building vertical crossed by DOT shield tunnel was simulated by 3D MIDAS/GTS software, and the impact of construction on the building was analyzed. The results show that: during the passage of the shield tunneling through the building, the settlement of the building increased. The settlement was stable and had a little rebound when shield machine already passed the building. The building’s longitudinal displacement was great larger than lateral horizontal displacement. With the increase of driving distance, the first principal stress P1 and maximum shear strain MSmax increased and then were stable. With the increase of L, the first principal stress P1 and maximum shear strain MSmax tended to gradually reduce the security value, and the maximum differential settlement between columns increased first and then decreased. Finally, the safety of the building was assessed comprehensively.

3D Analytical Solution of Soil Deformation Induced by Shield Tunnelling Construction

Three-dimensional (3D) analytical solution of soil deformation induced by ground loss in shield tunnelling construction was researched. It is put forward that the ground loss ratio is not a fixed value, but changes in driving direction. The calculation formula of ground loss ratio in driving direction was deduced. Based on two-dimensional (2D) analytical solution of uniform ground movement model of shield tunnelling, the three-dimensional analytical solution of ground deformation induced by ground loss is deduced. The settlement in vertical direction and the displacement in lateral horizontal direction at any point can be calculated; and the method is only applied to the construction phase. In analytical calculation: the predicted soil displacements are in good agreement with the measured values, and the method is easy to use; the closer the soil to tunnel is, the faster the lateral horizontal displacement changes; the extent of change of lateral horizontal displacement in longitudinal direction is smaller than displacement in lateral direction.

The Gujarat, West India, earthquake (Jan 26th 2001). A geodynamic event in an intraplate compressional regime?

The Jan. 26, 2001, Ms=7.7 earthquake occurred in Gujarat region of W. India, which lies 200-400 Km away from the active plate boundary zone, between the Indian subcontinent and the Asian plate, along the India-Pakistan border and the Himalayan belt. An Ms=7.7±0.2 earthquake also occurred in the same region in 1819. A zone of co-seismic E-W surface ruptures, 30-40 Km long and 15-20 Km wide, observed near the epicentral area and seems to be associated with pre-existing reverse faults and thrust folds, which were partially reactivated during the recent earthquake. Except the reverse vertical displacement a significant right lateral displacement was also observed along these E-W surface ruptures. This Ms=7.7 seismic event has been also accompanied by a large scale flexural-slip folding, as the absence of significant co-seismic fault displacement and fault scarp shows. This type of compressional tectonic deformation is also confirmed by the focal mechanism of the earthquake and the seismo-tectonic "history" of the area. The NW-SE open cracks, also observed along the same zone, are associated with the right lateral horizontal displacement of the reactivated fault (or branch faults) and the development of local extensional stress field in the huge anticlinic hinges of the co-seismic flexural-slip folds. A large number of ground ruptures, failures and open cracks are also associated with extensive sand boils, liquefaction phenomena and lateral spreading.

A simple graphical method for estimating the components of the fault-slip vector

A simple calculation of the components of the total slip vector ( D) on a fault plane allows the relationships between the magnitudes of the three slip components of D, the lateral horizontal displacement ( L), the transversal horizontal displacement ( T) and the vertical offset ( V), to be determined. The contribution of each slip component to the total slip can be plotted jointly in a ternary diagram, assuming a unit length of the vector modulus and a suitable normalization for D. Each component equals the magnitude of D at the vertices of the diagram, hence it is possible to estimate the percentage contribution of each slip component to the total movement of a fault or a set of faults. The dip of the fault surface and the rake of the slickenlines are the input data required for displaying L, T and V relationships in these diagrams. This information may be useful in the analysis of movement geometry for different fault populations and in the determination of D by measuring just one of the fault-slip components, such as vertical slip associated with a fault scarp.