AS 8700:2011 pdf free download – Execution of prefabricated verticaldrains

AS 8700:2011 pdf free download – Execution of prefabricated verticaldrains.
AS 8700 provides general requirements for the execution, testing. supervision.
monitoring and installation methods of prefabricated vertical drain projects. It also includes information on design considerations, and practical and design aspects of vertical drainage.
Prefabricated vertical drains are used for the improvement of low-permeability, highly compressible soils, and in on-land and marine constructions for—
(a) (pre)consolidation and reduction of post-construction settlements; speeding up the consolidation process by decreasing the path lengths for pore water dissipation;
(b) increasing soil stability (by increasing effective stresses in the soil);
(C) groundwater lowering; and
(d) mitigation of liquefaction effects.
In each case there is an overall treatment of the soil (the volume of the drains is small in relation to the soil volume treated).
Prefabricated vertical drains may also be combined with other foundation or ground improvement methods (e.g. sand drains, vacuum consolidation, electro-osmosis, piles and compacted sand piles, rigid inclusions, dynamic compaction and deep mixing).
NOTIS:
I See References 1. 2. 3 and 4 in the Ilibliography.
2 Guidance on practical aspects of prefabricated vertical drains, such as investigation of drain properties, execution procedures and equipment, is given in Appendix A.
3 Guidance on the evaluation of soil characteristics and design considerations is given in Appendix B.
1.2 NORMATIVE REFERENCES
The following are normative documents referenced in this Standard:
NOTE: Documents referenced for informative purposes, including material referred to during the
preparation of this Standard, are listed in the Bibliography.
2.4 PREFABRICATED ROUND DRAIN
2.4.1 Shape and structure of round drain
A round drain consists of an annular-corrugated and perforated open circular core, surrounded by a filter sock. The drain diameter is typically 30 mm to 50 mm in outer diameter and 5 mm in wall thickness.
Tears and/or other defects shall not be allowed to occur in a round drain. Visual inspections for damage shall be made regularly as part of the production quality control.
2.4.2 Measurements
The diameter and thickness of the core shall comply with the dimensions given by the manufacturer (within allowable deviations given by the manufacturer).
2.4.3 I)urahllitv
The durability requirements for round drains shall be in accordance with Clause 2.3.3.
2.4.4 Tensile strength and elongation
The required tensile strength of the round drain is dependent upon the type of installation machine, installation technique and depth of the drain.
Tensile strength of the drain in the longitudinal direction shall he high enough to prevent breakage during and after installation.
Testing of tensile strength and elongaion of the round drain shall he made in accordance with the standard tensile test with modified clamps (see Table 2.1).
The strength of the seam, measured according to the relevant Standards listed in Table 2. I (with modified clamps) in a range of temperatures that apply to the project site, shall be at least I kN/m.
The grab tensile strength of the filter shall be greater than 0.3 kN.