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State-of-the-art report

Penetration testing in Japan

T. Muromachi, I. Oguro & T. Miyashita

The present State of the penetration tests in Japan is reported. Since the Standard Penetration Test has been most widely used in our country for subsurfacc investigation in nil pur-poses, the boring method, penetrometer and devices, test procedurę and interpretation and evaluation of the test results, especially the use of "JV-values" are fully reported. With respect to the other soundings, the Swedish sounding, static deep soundings including the Dutch cone-penetrometer and also static penetration test with light portable conepenetrometers are reported briefly.

The Standard Penetration Test is fołlowed by the Swedish Sounding and the Deep Sounding with Dutch Cone-penetrometer. The former is often employed as a suppliment to the Standard Penetration Test or for the purpose of prelimi-nary survey, while the latter is often utilized for detuilod survey of normal subsurface condi-tions with AT<30.

For oxtremeiy weak ground with N - 0 or for the ground so weak that the inner rod of the Dutch conc-penetrometer sinks by its own weight, a portable, light-weight cone-penetrometer is used.

Tm	Opcrtu*		(AMmmm)
	Or—c		T#ti	iis A-imtmo
	(Drop Htfwr)		Dfim Cam łWwattif	• X) RTHKWM) T
NorMlTr*.				JSSUFE StamltnMIKD
	3 {/)	PmiriOort	Dnich Com P««iwwur	JSSMft Si*»kftl(l9W)
		WiiMrtwal		• X) RTRMJNH) Tr*
	Drmak <Dn* Kaamr)		Tm Cant P»n»inmł##	• IS) INAI< Wo#k« KtMtrth Inn. (Sabo Tm>
	Suoc			• 2) RTKI- | Tm
	(ISo#<#*oanJ		CWU-Mb* Typ* Corm Pwww	• 2) RTRI-3 Tm
VctarW-	i rj	WidSmiJ	Ca#	CcłUi Ca Tm
Tm		Pv«Uitxn	S* | Ccnv Ca#	Fapt* Tm

1. INTRODUCTION

1.1 Status of penetration tests in Japan

Penetration tests presently employed in Japan are summarized in Table 1. In terms of freąuency the Standard Penetration Test comes at the top of the list; virtually all the explora-tory borlngs are accompanied by this test and the "tf-values" are widely accepted in thls country.

Table - 1 Representative Penetration Tests in Japan ( by T . Muromachi)

In addition to the above, the Dynamie Cone Penetration Test and Puli-sounding (Iskymeter) Test are occasionally conducted by some organi-zations in Japan, but their use is limited as com-pared with the other methods.

A few engineering contractors in Japan have developed vehicle-mounted cone-penetrometers and put them to practical use with success for subsurfacc investigations of large construction sites.

1.2 Geological settings

Being a part of the circum-Pacific oroge-nic zonę, Japan has undergone violent orogenic movements for ages. Formations which emerged in each age have heavily folded and usually they are disturbed by intrusions of igneous rocks or developments of fauits. Relatively horlzontal bedding is retained only in formations deposited after the latter Pliocene in the Tertiary period.

In this geological history, lithification of strata deposited in different ages has advanced; thus even the formations from Pliocene to the early stage of Diluvial cpoch have been hardened so much that they indicate unconfined comprcssion strengths of 10^30 kg/cm?

Thus the strata to which these penetration

Geologie ir				Strtu	RepresemaUw Wow counti	Uirfulnrii of penetrometera				CcoicchnicaJ not**
						S.P.T.	Dutch eon# K	SwudJah aoundlnc	Por table eon# P.
i £ l	AltwiaJ cpoch		Aficr pre-Boreal sug*. Approju/nateły 10,000 yetri.	CU,	0-5	O	o	o	o	Eaplorable by acwral penetration tesla. Those escept the S. P.T. aro genorally appficd fo inwiLigmuon of weak aoila and the oorutruction control of the itsbiliied foundition
				Sand	<20	O	o	A	A
				Sand and Crawl	<30	o	A	—	—
	i Ul	Uur tu<«	Froca RisfWurm knur-głac»al lUft to •uro gUctal iU|f. uc. betwecn Wraoauly 10,000 yetn ifo froca and 150,000 yeart agu.	CU,	3-7	o	o	A	—	The pmetrobon triu irt tpęited to fmd lho betring •irau but only the S.P.T. la can bo appUcable bocauao of tho high •trmgth* of the itr* u. O • F re^uemfy used A : Occastonally used — I Scorcrł, w<d
				S*nd	10-30	o	A	—	—
				S*oJ *nd Cr**rl	30- 50+	o	—	—	—
		MkUle ■u«t>	From COnzMtndH imer-gUcitl tuge u> RU* gUciol iU(r- Lt. bol««n •pproxim*icly 150,000 ynrs ago to 800.000 ytiri ago.	CU,	10-30	o	—		—
				Sond	20- 50+	o	—	—	—
				Sand and Crawl	50<	o	—	—	—
		Etrltir IU|«	Fron Domu eoider łjt to Gunz gUciol i-c. btmtfl •ppraunetrJ, 600,000 *«o to Ł000,000 yt*r» tgo.	CU,	30<	o	—	—	—
				Sond	50<	o	—	—	—
				Sand and Crawl	50<	o		—	—
Tertiary Period		Pliocene			50<	A	—	—	—

Table - 2. Penetrometers for strata formed in each Geologie age in Japan (by J. Oguro)