L

—[monitoring | J—[performance of the treated soil | -[other aspects }

Special requirements

-[ records during construction } -[ records at completion of the works""}

-[safety } —| environmental protection } -[impact on adjacent structures }

A description of deep vibratory compaction and its applicability is given in Annex A. Annex B describes the process of installing vibrated stone columns and gives recommendations regarding their applicability.

Detailed design methods are not provided but helpful guidance is given on design principles and matters that require consideration when selecting and constructing deep compaction columns.

Emphasis is placed on the use of in situ testing to monitor the improvement of ground properties due to deep vibratory compaction, utilizing cone penetration tests, dilatometer tests, dynamic probing, pressuremeter tests, or standard penetration tests. Similar tests may be used for vibrated stone columns but consideration should also be given to large scale load tests. Plate loading tests should be carried out on individual columns.

EN 14731 was published by CEN in 2005 and is due for systematic review by TC 288 in 2010.

15.4.5 Vertical drainage

Figure 15.14 summarizes the scope of EN 15237,21 which deals with the execution of vertical drainage including prefabricated vertical drains and sand drains. The standard deals with the requirements for design, drain material, and installation methods for providing vertical drainage for pre-consolidation and reduction of post construction settlements; increasing the rate of consolidation; increase of stability; groundwater lowering; and mitigation of liquefaction effects.

EN 1237 does not cover soil improvement by other methods such as wells, stone columns, or reinforcing elements.

EN 1237 discusses testing of various types of drain: band drains, prefabricated cylindrical drains, and sand drains. For prefabricated band and cylindrical drains, the following are covered: shape and structure measurements; durability; tensile strength and elongation; discharge capacity; filter, its tensile strength and pore size; velocity index; and quality control. There are extensive references to other EN ISOs covering testing of the various elements of drains. This requires a large number of standards to be referred to when specifying prefabricated drains.

It is essential that the consolidation process is monitored to verify that the drains are performing according to expectations. Where necessary, field trials should be carried out to verify the design spacing and depth of drains.

Normative references \

{Terms and definitions special features for çround treatment by deep vibration

Information reeded for the execution of the works

Normative references \

deep vibratory compaction vibrated stone columns supervision and j vibratory compaction monitoring J\ vibrated stone columns deep vibratory compaction vibrated stone columns supervision and j vibratory compaction monitoring J\ vibrated stone columns specific aspects for deep vibratory compaction specific aspects for vibrated stone columns

Geotecftnical investigation

Scope of EN 14731 Execution of special geotechnical works -ground treatment by deep vibration

Supervision, testing, and — /deep vibratory compaction monitoring vibrated stone columns mate rials

| materials for deep vibratory compaction

| materials for vibrated stone columns ■[selection of treatment method""

| materials for deep vibratory compaction

records in connection with the execution of the ground treatment records at completion of the ground treatment

Figure 15.13. Scope of EN 14731, Execution of... ground treatment by deep vibration records in connection with the execution of the ground treatment records at completion of the ground treatment

{design verification)— Considerations related to design

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