Search results for: Latest H19-461_V1.0 Exam Questions Vce π― H19-461_V1.0 Labs π H19-461_V1.0 New Study Plan π Search for β H19-461_V1.0 οΈβοΈ on γ www.pdfvce.com γ immediately to obtain a free download π§H19-461_V1.0 Best Vce
-
Pile settlement zones above and around tunnelling operations
This paper describes briefly the method of analysis of the response of a pile to tunnelling-induced movements, including estimation of the loss of axial capacity. The various pile settlement βzonesβ computed from this analysis are compared with those measured experimentally for tunnels in sand by Jacobsz et al. (2001). Some theoretical differences are identified between the cases of tunnels in sand and in clay. Finally, for an example case of a structure over a tunnel, a comparison is made between the performance of three alternative foundation types, a piled foundation, a piled raft foundation and a raft foundation without piles. It is shown that the tunnelling induced movements have less influence on the latter two foundation types than on the fully piled foundation.
-
Sydney Sandstone geomaterials – Broken, crushed and friable rock products
Sandstone in fragmented form, derived from the Hawkesbury Sandstone, the Banks Wall Sandstone and the Terrigal Formation, is β by geological default β an important and growing source of geomaterials in the Sydney area. Although of only moderate strength and durability, this sandstone breaks down to produce well-graded sand with a soft gravel fraction and low plasticity fines. Crushed sandstone is good to excellent as earthfill, adequate as rubble, but is unreliable as rockfill for dams. It performs well as slope protection stone in embankments and the more durable sandstone is sometimes suitable for marine breakwater stone. It has been used in the past for concrete aggregate, especially in βcyclopean masonryβ dams, and is still employed as aggregate to a very limited extent in low-strength backfill and bound sub-base. Crushed sandstone is, however, generally unacceptable for unbound pavement courses because of its high inherent clay content (up to 30% <75 um), water sensitivity and only moderate particle strength. Its dry UCS is typically 10-30 MPa, and only 30-80% of this value when wet. Two important and growing sources of sandstone geomaterials are tunnel spoil (about 2 Mtpa) and quarried friable sandstone (also about 2 Mtpa). The environmental impact of sandstone quarrying is generally positive, in that it substitutes for scarce sources of high value hard rock. Because sandstone is nearly ubiquitous around Sydney, quarries can be sited in areas of low scenic value, require no blasting and can be shaped to productive end-uses. However, sand washing generates 10-30% of clay tailings, which are deposited in slurry lagoons, some of which have collapsed in the past due to inadequate spillway capacity. Although the tailings are a potential source of kaolinite and brick clay, cost-effective methods of de-sanding and dewatering have yet to be developed.
-
Effect Of Clay Structure Degradation On Settlement Of Embankment
Due to the degradation of initial structures, soft clays can experience significant settlement without much change of pore pressure. Such a phenomenon has recently been observed at a fully instrumented trial highway embankment near the town of Ballina (New South Wales, Australia). In contrast, the displacements in saturated soils without structure (such as a fully remoulded clay) are always associated with the dissipation of excess pore pressure through the effective stress principle. This paper demonstrates the effects of clay structure degradation on the settlement of embankments, through numerical analysis of a trial embankment on soft clay. A constitutive model that accounts for destructuration of soils is used to characterise the behaviour of the soft clay. The material parameters are derived from conventional oedometer and triaxial tests for the structured constitutive model. It is shown that the settlement and the dissipation of excess pore pressure during construction of the embankment are closely related with the destructuration of the soft clay. With appropriate choice of the constitutive model and material parameters, the lag between the settlement and pore pressure dissipation can be well predicted by the coupled finite element method based on the effective stress principle and consolidation theory.